Deathstroke (Arrowverse)/Synopsis

Early life
Slade Wilson was an Australian Special Intelligence Service’s operative with a partner named Billy Wintergreen. Slade also had a son named Joe who he picked Billy to be the godfather of. He also had another son named Grant Wilson who would take on his father's name and appeared as a villain in the spin-off series Legends of Tomorrow in a potential future in 2046.

Plane crashed on Lian Yu
In 2006, Slade and Wintergreen were tasked with rescuing Yao Fei, a former Chinese military commander purposely shipwrecked on the island by his government to conceal a massacre they perpetrated 8 years earlier, and uncovering the plot of Edward Fyers who held Yao Fei hostage for reasons unknown to them. However, their plane was shot out of the sky whilst on route towards the air strip, and the two were captured by Fyers’ men. Fyers offered the two men to join his cause. Whereas Slade refused, Wintergreen accepted. Slade was held in the camp for over a year until Yao Fei freed Slade. The two took refuge in the wreck of Slade's plane. They planned to escape the island by stealing a supply plane on an air strip, but before they could do so, the two were separated.

Facing Edward Fyers' and meeting Oliver Queen
6 months later, Slade caught a young Oliver Queen, who had been shipwrecked there, searching through his hideout. Oliver explained Yao Fei had sent him, but viewing him as a liability, Slade attacked and knocked Oliver unconscious. He bound Oliver to a chair by his wrists. When the other man woke up, Slade explained to Oliver that he had to kill him, just before Oliver freed himself by dislocating his thumb. Oliver went on to punch Slade in the face, convincing Slade that he was worth keeping alive. Slade told him he needed another to implement the plan he and Yao Fei had made to steal the supply plane. While choosing a weapon, Oliver found Slade's mask that was identical to that of Wintergreen, who had tortured Oliver at Fyers' camp when he first arrived on the island. Not realizing it was another mask, Oliver accused Slade of deceiving him, but Slade explained both he and his ex-partner wore the mask to protect their identities, as well as their allegiance to ASIS and their mission.

Slade attempted to train Oliver to fight, to not much success, until he gave the younger man the option to escape or die. They had only ten days to train before the plane arrived on the island. On the tenth day, they started their journey towards Fyers' camp. On the way, Oliver stepped on a land mine, presumably left behind from World War II. When some of Fyers' men approached their position, Slade killed them and used one of their bodies to free Oliver. That night, Slade revealed Oliver that Wintergreen had betrayed him immediately after their capture and that he was the godfather of Slade's son. Once they reached Fyers' camp, Slade proceeded to take out the soldiers with his sniper rifle, as Oliver reached the communications tower, with his only duty being to kill the man there. Oliver failed in his task, but Slade managed to get there in time to kill the man right before he shot Oliver. Slade told Oliver he would call in an airstrike to blow up the island after they left. Concerned about Yao Fei, Oliver left to bring the other man back with him. Slade stayed behind and told him he had three hours or he would be left behind. Despite what he said, Slade went back for Oliver and saved him from Wintergreen. He managed to kill Wintergreen, but was shot in the arm by Fyers. Slade acknowledged Oliver had proving himself to be a fighter.

Slade's wound is infected, forcing Oliver to head out to find herbs which could fight the infection. Oliver came back with the herbs and claimed not to have encountered any problems. When Oliver attempted the fix the damaged radio they had obtained from the communications tower, Slade joked "pigs would fly" before he succeeded. Ironically, Oliver managed to repair the radio, shocking Slade. However, they discovered the radio could only receive, but not transmit, so they could not use it to call for rescue. As Slade listened to the soldiers' frequency, he overheard Fyers talking about something called Scylla to an unknown man. Oliver explained Scylla was a monster in the Odyssey by Homer. The two men left to discover what Scylla was and found it was a missile launcher.

To get closer to the missile launcher, Slade pretended to be a prisoner taken by Oliver. The ploy worked, and Slade managed to kill all the guards around the missile launcher. Just as he was about to destroy it, Oliver stopped him and took out the circuit board instead, effectively stopping the missile launcher from working. Slade was excited to have a leverage over Fyers. Oliver contacted Fyers and arranged to trade the circuit board back to him in return for a way off the island. At the meeting, Fyers questioned if he could trust them to be truthful. Slade answered he himself would not, but Oliver had a thing for principles. Fyers took advantage of that and brought out Shado, Yao Fei's daughter. When Fyers threatened to kill Shado, Slade attacked him, providing enough distraction so he and Oliver, along with Yao Fei and Shado, could escape. On the way, Yao Fei was shot, and he told the others to leave him behind. When they returned to their hideout, they discovered that the circuit board was missing. Slade was angry at Oliver for being played, until Shado pointed out that Fyers could not risk them leaving the island with their knowledge anyway.

Slade started sparring with Shado, with the two proving to be equally matched. When Shado asked how well a fighter Oliver was, Slade answered he had tried to train Oliver with limited success. Shado decided to train Oliver himself, and Slade left them to it. When he returned later, Slade found Oliver slapping a bowl of water and found out he had been doing it all day. Shado claimed the exercise built strength, and was proven correct when Oliver managed to draw the bow in their possession, impressing Slade with the technique. Later, Slade discussed how to rescue Yao Fei with Shado and came to the conclusion they would need someone else to watch their back. Slade refused Shado's proposal to have Oliver do it with the bow, saying he was not ready. Shado took Oliver away to train, and told Slade if he was not ready by the end of the day, they would try a new plan. When they returned, Slade found out Oliver had failed at hunting down an animal. Before they could formulate a new plan, however, Yao Fei arrived with Fyers' soldiers to surround them. Angry at Yao Fei's betrayal, Slade attacked Yao Fei but was knocked down by one of the soldiers.

Fyers took the three back to his camp. When he wanted to make a point to Yao Fei, he shot Slade in the leg. Slade witnessed Yao Fei's death when Fyers had no more use for him and shot him in the head. Slade, Oliver and Shado managed to break their bonds and attacked Fyers and his men. Slade survived the blast from the missile launcher and joked Oliver could not save the day without making a mess. Fyers arrived with Shado, revealing he had survived the blast, and angry at Oliver for ruining his two-year operation. Oliver killed Fyers using Yao Fei's bow, impressing Slade that he could kill.

Shado's death and betraying Oliver
5 months later Slade continues to mentor Oliver. While sparring, Oliver gets distracted and he hits him saying, "You're not the first one to learn the hard way. Women are a distraction". A few minutes later, a proximity detector device they had salvaged from the wreckage of Fyers' camp goes off, and they go looking for the people the device had detected, but Shado is quickly captured and Oliver and Slade chase after her. Later, Slade and Oliver catch up with Shado and the people who captured her. Slade tries to stop Oliver from doing anything rash, but the leader hits Shado, and Oliver becomes enraged and attacks the leader while Slade attacks the others. Slade and Shado are shocked when Oliver is unable to control himself and kills the leader. Moments later, Slade picks up a radio that goes off, and the three are left wondering how many more men are on the island and where they came from.

Slade talks to Shado and, knowing what he's going through, asks her to comfort Oliver. He finds a map, similar to the one provided to him by ASIS. Later, Slade sees Oliver and Shado by the river, becoming closer. He reminds Oliver that women can be a distraction, and that that can get him killed, as they leave the riverside. They go to the location in the picture, and Oliver soon after directs him and Shado to a cave. There he discovers a blade, in which he says is 60 years-old, and they also discover the remains of World War II Japanese soldiers. Slade has Oliver tag along with him to scout for the new threat to the island, telling him that Shado can take care of herself as they leave. As they are going up to higher ground, Slade once again reminds Oliver that woman can be a distraction, while in conversation Slade almost falls off the cliff side if not for Oliver catching him in time. Slade and Oliver make it to the top of the cliff and spy the ship firing at a fixed location where they work out is where the plane is which causes Oliver to run with Slade giving chase. Slade is chasing Oliver while the area is still under fire. Slade is last seen being hit by an explosion, with his hands and the right side of his face on fire, yelling in pain.

Slade survived the attack and is seeking refuge on the island. The explosion has left severe burns on one side of his face, however, as Shado tends to his wounds. Despite his warning to leave him for safety, Shado declares that she is here to stay, and would never leave anyone she cared for alone. Slade is still weak and extreme pain, with a herbal ointment covering to the right side of his face. When Anthony Ivo's soldiers attack the plane, Slade and Shado hide. Although quite bruised, they later managed to rescue Oliver and Sara Lance from Ivo. Oliver says that if they find the serum, it could possibly heal Slade's wounds. The group find the submarine and the Mirkauru on-board but can't find a sedative to give Slade first. Oliver gives Slade a choice as the injection without a sedative could kill him but Slade agrees but before Oliver gives it to him he confesses his romantic feelings for Shado. Oliver then injects the Mirakuru into him. The injection causes blood to come out of his eyes, and then he collapses into unconsciousness though the others believe him to be dead. When Ivo catches up with the group he checks Slade's pulse and appears to be dead. But Slade awakens a few minutes after his injection with Mirakuru, calling Shado's name. He runs to the site where Ivo has killed Shado, and thanks to his Mirakuru-enhanced physical capabilities, he easily slaughters Ivo's men. He then picks up Shado's body and vows that the person responsible for her death will suffer.

Slade, Oliver and Sara bury Shado next to Yao Fei and Robert Queen's gravesites where Slade hands Oliver Shado's hood acknowledging that Oliver was the one she cared for. Later Slade wants to get geared up to kill Ivo and his men but Sara tells him that he can't handle it by himself but this enrages Slade as Sara was working for Ivo but when Oliver tries to break them up, Slade starts chocking Oliver to death until Sara uses a tree branch to stop him before he Sara tells him that the Mirakuru is affecting his mind. Later without Sara or Oliver, Slade takes the Mirakuru serums and heads after Ivo himself. Slade uses Fyers’ missile launcher and intended to open fire on the freighter until he was confronted by Oliver and Sara who threatened to kill Oliver but he managed to make him see reason using Shado and Joe. He then sat down and questioned what was happening to him, Oliver promised him that he wasn't going to give up on his friend and soon proclaimed they were going to take the freighter from Ivo. Slade, Oliver and Sara are observing Ivo's ship from a cliphead until they hear a plane flying overhead. The three try to get it's attention but it is shot down, the pilot dying. Slade and Oliver rush back to the plane to get medical supplies but arrive too late. They do however find a parachute in the pilot's plane.

Slade observes Oliver’s training and is impressed. Slade agrees that they should burn the last remaining Mirakuru prior to their attack on the freighter. Before attacking the ship Slade notes the first time they attempted to escape was as strangers but now was as brothers. As they reach the freighter, Slade tells Oliver and Sara not to kill Ivo as he wants Ivo for himself. Slade learns the truth about Shado after listening in to Oliver and Ivo's conversation. An enraged Slade attacks Oliver violently but Oliver slips away from him as explosions occur on the freighter. As Oliver attempts to escape the freighter, Slade grabs Oliver by the leg and imprisons him. When the Butcher, the ship's captain orders him to enter the cell with Oliver, he refuses. He crushes the skull of the Butcher who attempts to shoot him and declares himself the new captain. Later, he would ask Ivo to show him how he killed Shado and then lacerates Ivo's hand. Slade then promises to Oliver he will make him suffer in the same way he suffered before killing him.

Slade continues to torture Oliver on the Amazo while having his crew repair the ship, but are unable to repair the damage to the engines. Slade contacts Sara on the island and demands that Hendrick Von Arnim, an engineer who escaped in the siege, be handed over or Oliver dies, electrocuting him in the process. Slade also brands Oliver with the same tattoo Shado had to remind him of her death until his death, eventually Sara also agreed to hand Hendrick over. Slade returns Oliver and Ivo both to the island in exchange for Hendrick, who has been secretly rigged with explosives, but as his men take him outside Slade senses the explosives due to Mirakuru and removes and disables them. He then wants to kill Sara and Oliver but has a hallucination about Shado who tells him to leave them on the island forever. As Slade walks outside he tells Oliver that once the ship is ready, he is going after his family. Later Slade had his men take Sara on the island and locked her in a cell. When Oliver sneaks aboard to free her and find the Mirakuru cure Ivo mentioned, Slade was waiting with the cure in his hands and had Oliver and Sara captured.

Slade forces Oliver and Sara to watch as he injects unwilling prisoners with the remaining Mirakuru, having become obsessed with making others like him, but Oliver and Sara pleaded with him to release them and to come to his senses, but his hallucinations of Shado instead convince him to kill them. He puts his mask on and prepares to kill both, but Anatoly fires a torpedo from the submarine, which causes the ship to split in half and Oliver uses the chance to destroy the Mirakuru in a resulting fire. But Slade engages Oliver and throws Sara into the split which apparently causes her to drown. Oliver out of anger attempts to fight back but is completely outmatched. Before he can kill Oliver however some rubble falls from the ceiling and traps Slade. Oliver has the choice to either kill Slade or cure him. However, after more taunts from Slade, Oliver chooses to kill Slade by stabbing him in the eye with his arrow. The ship sinks and Oliver is saved by A.R.G.U.S. from the remains of the ship.

After Lian Yu
While it was presumed that he was dead, Slade in fact survived Oliver's attack. He swam to the nearest coast line but was cut down to the bones by the rocks and debris in the ocean. The Mirakuru regenerated everything but not his eye. After the island Slade attempted to forget everything that happened but it would still haunt him. Slade would eventually become a mercenary that A.R.G.U.S. would codename "Deathstroke", but A.R.G.U.S. remained unaware of his true identity.

Mirakuru plot
When Oliver became the Starling City vigilante called Arrow/Hood and exiled himself back to the island after failing to stop Malcolm Merlyn’s undertaking, Slade planned a mission of vengeance to destroy Oliver and Starling City with an army of Mirakuru soldiers, to cause enough damage to force Amanda Waller to airstrike Starling City and leave nothing left. He became associated with Isabel Rochev who he planted in Queen Consolidated to take over in order to draw Oliver back, but also to seize control of Oliver's company so that he would lose everything from his funds, house, his Arrowcave and even his former club. He also trained Isabel how to fight which she claims almost killed her.

Slade also became associated with Alderman Sebastian Blood and funded his mayoral campaign and promised him control of the city using an army of Mirakuru soldiers to reduce the city to a state of desperation and in that desperation the people would turn to Blood for guidance. In reality Slade simply needed Blood to prevent the national guard from intervention. To create his serum Slade had Sebastian use his influence to put together a cult to find people to test a new strain of the serum on and would manipulate them using a skull mask masquerading as “Brother Blood”

Oliver begins suffering from psychological hallucinations Slade being one of three deceased friends he sees. Oliver first sees "Slade" when talking to Quentin Lance about Cyrus Gold on a rooftop. Later when Oliver is practicing archery in the cave "Slade" reappears catching his arrow, but Oliver states that he is dead and can't be there before "Slade" criticizes Oliver's mission claiming it's not for his father's sins but rather his own. "Slade" then attacks Oliver throwing him around the cave telling him it's time to join him in death before disappearing. Contrary to what Oliver believes though, Slade Wilson remains alive in the modern day and is the true leader of the Church of Blood, allowing Sebastian Blood to use the Mirakuru from his blood to make more. Afterwards Sebastian asks him if he knows who The Arrow is. Slade confirms and informs him that he is his friend, and he will not stop until he has taken everything and everyone the Arrow values. Then he will drive an arrow through his eye.

Slade arrived in Sebastian's campaign office reading the police report of his father's murder which he obtained days earlier as Oliver and Laurel were onto Blood, criticizing Sebastian for almost allowing Arrow and Laurel Lance to obtain the file, and ordered Sebastian to take care of Laurel, reminding him not to let him do it himself. After Laurel and Oliver kill Daily impersonating Brother Blood, Sebastian and a set of body guards arrived in Slade's office informing him, Deathstroke however attacked, killing the three body guards and warned Sebastian that if he failed him again, he would kill him too. After watching Moira Queen's announcement to run for mayor Slade reprimands Sebastian for not taking Moira seriously but despite Sebastian's offer to handle the situation, Slade insists he will handle it personally.

Slade visited Moira in person who when Oliver returns home introduces Slade to him, unaware of Oliver and Slade's history together, which leaves Oliver in a state of shock. Slade continued to socialize with Moira and Oliver but secretly taunts Oliver about their past and is offered a tour of the Queen Mansion by Moira Queen and Thea, but secretly planted bugs with cameras all over the house. During the tour, Oliver calls Felicity to inform Sara that Slade is alive, and she and Roy Harper come to the house to discreetly intervene. When Roy introduces himself Slade notes his "particularly firm handshake" and realizes Roy is injected with Mirakuru before being stunned to see Sara alive, and Slade knows it's time to leave. Oliver offers to walk him to his car aware Diggle is planning on killing Slade, but he is secretly taken down by Ravager and Oliver works out that he is the true mastermind of Brother Blood's schemes. When Oliver asks Slade his intentions he simply reminds him of his promise before leaving. He later watches everyone in Queen Mansion through the cameras. Deathstroke tails Oliver as he searches for him, taunting him by leaving the same tattered mask from the island to mark his death. He later kills Alexi Leonov who had dug up information on him, leaving him to be found by Oliver when he sneaks into his office. Realizing that Slade is too good for him to find on his own Oliver infiltrates A.R.G.U.S. There he informs Amanda Waller that Slade is alive. Amanda realizes Slade is the same, previously unidentified mercenary A.R.G.U.S had tracked operating in several countries, nicknamed "Deathstroke". To obtain new soldiers for his Mirakuru army Slade plans to abduct Thea to cause a citywide diversion in order for him to hijack an upcoming prisoner bus transfer.

An upset Thea is walking home from the club when Slade stops his car to offer her a ride home. Slade acts concerned about Thea during the ride but when Thea realizes they did not arrive at her house he yells that she is not going home then demands she get out of the car. She runs from the car straight into Brother Blood who abducts her. Deathstroke announces his actions via video question at the Starling City Mayoral debate. The video shows Deathstroke with a bound and crying Thea; the video ends with a written message: "How much is Thea Queen's life worth?" After Felicity tracks Slade Arrow, Canary and Roy confront him but Slade neglects to tell where Thea is, despite Roy punching him in the face though with with little effect. Arrow then tells Roy to call Quentin to arrest Slade and afterwards shoots Slade with snake venom, rendering him unconscious. He is arrested but managed to falsify an airtight alibi and is subsequently released. Before he is released Oliver sneaks into the room to talk to him and begs Slade to tell him where Thea is but Lieutenant Frank Pike releases him before he answers. Oliver, Sara, Roy and Diggle try to follow his car but he gets away. Slade returns to Thea's holding place and tells her that she is free to go explaining to a confused Thea that he merely needed to prove a point, and the door is unlocked so she can leave anytime she likes but adds that she may never know Oliver's secret. Thea becomes confused and Slade offers to tell Thea what it is which she accepts and Slade tells her that Malcolm Merlyn was her father, and Oliver withheld this from him and lets her go. After learning of Isabel's true intelligence Oliver makes her tell him Slade's location and Arrow storms the building, taking down many armed henchmen but with no sign of Slade. Meanwhile Deathstroke stops a prisoner bus transfer in progress kills the guards and releases the prisoners, then Deathstroke informs them that he has a proposal for them all. Slade is then publicly exposed for being Thea's kidnapper. Slade later meets with Sebastian and Isabel in Oliver's office where Sebastian is frustrated that Moira is getting the voters support but Slade angrily tells him that he is holding up his end. When Isabel reveals that Queen Consolidated's applied sciences is ready to replicate Mirakuru Slade decides it's time to expose one more secret of Oliver's, again seeing a hallucination of Shado. He later turns up at Laurel's apartment and tells her that Oliver is the Arrow.

Team Arrow destroys Queen Consolidated's applied sciences to prevent Slade from mass producing the serum. Enraged by this and needing a new replacement for the applied sciences Deathstroke visits the Arrowcave and waits for the team. When they get back he fires at them repeatedly. Sara then charges him but Deathstroke strangles and tosses her into a table, tosses Diggle into the glass suit container and engages Oliver in hand to hand combat but easily over powers him before he leaves with the Skeleton Key, as Deathstroke reminds him who taught him to fight. Deathstroke uses the Skeleton Key to infiltrate a S.T.A.R. Labs facility to steal a bio-transfusor to take Mirakuru from once injected subject to multiple others at once. Deathstroke finds what he is looking for, killing the guard and chasing Caitlin Snow and Cisco Ramon through the facility to prevent witnesses but Cisco is able to use Arthur Light's special gun to distract him and made their getaway, though Deathstroke still escapes with the transfusor. Later Slade has Roy Harper abducted and uses his blood for the machine and Arrow finds it. However Slade was waiting with Isabel and the two fight him but Slade is temporarily knocked out by Oliver, Isabel is shot by Diggle and Roy is taken back. However the machine had served it's purpose and Slade now has his army, and uses his own personal blood to inject Isabel and restores her to life.

Slade used a truck to crash the Queen's limo. Whilst they were unconscious he tied Oliver up and held Moira and Thea at gun point in a scenario identical to Ivo holding Sara and Shado at gun point and also tolls Oliver to choose. Slade also mentions that he knows exactly how the scenario went down, claiming that Shado told him point to her but Oliver only sees the woods and realizes Slade is seeing hallucinations. Slade also exposed to Moira and Thea that he was on the island with Oliver and Oliver's relationship with Shado, but before he could force Oliver to choose Moira stood up and begged Slade to kill her instead. Slade aimed the gun but lowered it, admiring Moira's courage but expressing sorrow that she didn't pass it onto Oliver before impaling her with his sword. As Slade walked off, he tells Oliver that he will kill one more person before he kills Oliver, then leaves him and Thea to grieve. Slade's murder of Moira send Oliver into a state of depression and was even considering turning himself into Slade. However Moira's murder was also so Sebastian could become mayor of Starling which succeeded. Once Sebastian did become mayor Slade calls him, impersonating his father to remind him that he still works for him before hanging up.

As his army destroyed Starling Slade sat back and watched from Isabel's CEO room at Queen Consolidated. Later Slade, having tapped Oliver and all his allies' phones, learned of the Mirakuru cure from Central City and sends his bodyguard to retrieve it. As Slade continued to watch the destruction Sebastian barges into his office and demanded an explanation to why the entire D.A.'s office had been slaughtered and Slade gave none before angrily reminding Blood once again that he held up his end and that Oliver Queen must be made to suffer which will happen when Starling is nothing more than a grave-site. Slade later sent Isabel to kill Sebastian when he stole the Mirakuru cure telling him goodbye one last time.

Arrow and Canary, knowing the cure works and arming themselves with injection arrows, storm the office where Deathstroke, Ravager and a number of henchmen are waiting for them. Though Deathstroke was confident they could defeat the two, the League of Assassins, led by Nyssa al Ghul storm the office, defeated the soldiers and killing Isabel but Deathstroke was too heavily armored for the cure to work and escaped. Slade had Laurel kidnapped by also watches a video in Queen Mansion of Oliver telling Felicity that he loves her, much to Slade's shock, and kidnaps her also. After the army is defeated Slade informs Oliver of the kidnap and lures him to a foundtry, forcing him to choose between Felicity and Laurel, the way Oliver chose Sara over Shado. Arrow arrives and tries to talk Slade out of killing them. He also reveals he is aware of his hallucinations of Shado and that the real Shado would be horrified with what Slade has become. But as he defends his actions Felicity injectes a hidden syringe (with the Mirakuru cure) into Slade's neck, taking his strength away. He then dueled Oliver, for sometime but he managed to restrain Slade against a pillar, despite demanding that Oliver kill him. Some time later, Slade was incarcerated in a A.R.G.U.S. supermax on Lian Yu. Oliver visited him and tells Slade that despite all he'd done, his training and this plot is what made him not a killer but a hero and thanks him. As Oliver is walking out Slade angrily scolds him for believing he won't escape and yells to him that he keeps his promises as Oliver leaves.

Imprisonment on Lian Yu
In late 2014, Slade received a cellmate, Digger Harkness. In early 2015, Malcolm Merlyn released Slade and informed him Oliver and Thea were on the island, as Malcolm wanted them tested in order to help defeat Ra's al Ghul, and Slade set out to find them. After learning that Slade escaped Slade quickly attacked and knocked them both out and placed them in the Supermax. Slade said he would leave them on the island like Oliver did to him and telling him to be grateful that he didn't bury Thea next to Shado, then taunting Oliver about Shado's death again and stating that had he told him the truth himself Moira may still be alive. Slade told Thea that her brother always will keep secrets for her, before leaving them behind. However Oliver and Thea were able to free themselves and pursued Slade as he attempted to use their plane to escape. Slade ambushed them and took Thea hostage with a gun, but was surprised when she fought back and Slade fought both Thea and Oliver simultaneously, before Thea pulled a gun on him and wanted to kill him. However, Oliver managed to convince her not to kill Slade, but she still shot him in the shoulder. Returning to the Supermax, Slade noted that Thea was not the killer Oliver was. As Oliver was leaving Slade taunted him about the people he had lost and how losing any more would leave nothing of Oliver Queen.

Oliver returns to the island to recruit Slade and Digger to his team in a rescue mission to retrieve his team and son from Prometheus and in exchange, he gives Slade files on his son Joe. Slade is shown to be a lot more sane, having purged the lingering effects of the Mirakuru from his system during his incarceration. Slade is stunned that Oliver would want to help him after having killed Moira and Oliver's decision to ally with Slade receives backlash from Thea as well. Slade proves his loyalty to Oliver by refusing to ally with Prometheus' gang when Digger offers and helping Oliver sneak Dinah a device to restore her powers by feigning a defection and getting Oliver captured. Prometheus later commits suicide after failing twice to goad Oliver into killing him, causing Lian Yu to blow up due to a dead man's trigger, leaving the fates of Slade, Diggle, Felicity, Dinah, Quentin, Thea, Curtis, Nyssa, Evelyn, Black Siren, Talia, Rene and Samantha unknown.

DC's Legends of Tomorrow
In the episode "Star City 2046" it is revealed that Slade had another son named Grant who in one possible timeline took up his father's mantle as "Deathstroke" and attacked Star City with an army once more. This resulted in the deaths of everyone on Team Arrow, minus Felicity who left in grief and Oliver who's left arm was cut off by Grant and went into hiding. However Oliver, using a cybernetic arm, and Connor Hawke (his successor) are able to defeat Grant (ironically almost the same way Slade was defeated).