The story of Peridot from Steven Universe series.
Season 1[]

Peridot in her first appearance.
Peridot first made her debut towards the end of the episode "Warp Tour", where she was tasked with scouting the Galaxy Warp to fix the damaged warp pads and repair the Gem Kindergarten, but was distracted by one of her damaged Flask Robonoid and unmercifully crushed it to death. She then sees Steven's "Crying Breakfast Friends" sticker, and, fearing the site may be compromised, deactivates her Robonoids and presumably retreats back to the Gem Homeworld to tell the other Homeworld gems.
Peridot appears as the main antagonist in the episode "Marble Madness" where she sent multiple Plug Robonoids to Gem Kindergarten in order to activate Facet Five. As she was doing so, she discovered Steven trying to chat with her and he wanted to know what Peridot is doing sending the Robonoids to Earth. Annoyed, Peridot tried to crush Steven with her giant stone gloves, but, much to her surprise, she was foiled by Garnet. A paranoid Peridot, still confused about the Gems's existence, tries to kill them, but Amethyst uses her whip to toss one of her stone gloves into the projection destroying it. However, as the video pans out, Peridot threatens to report the Crystal Gems's existence to the higher Gem authority.
Peridot appears in the half-hour special episodes "The Return" and "Jail Break", assisted by Jasper and a captive Lapis Lazuli. Peridot, under Jasper's orders, attempted to kill the Crystal Gems but was stopped when Steven summoned his shield. She is later shown to be very angry when Jasper orders her to forget about the mission, saying that bring "Rose Quartz" (Steven) to a Gem known as Yellow Diamond takes priority over the mission. Peridot begrudgingly returns to the bridge to pilot the ship back. Later, after Steven frees Pearl and Amethyst, the three storm the bridge and Amethyst ties up Peridot with Pearl taking control of the ship and piloting it back to Earth. After Garnet defeats Jasper and the ship begins to crash, Peridot takes an escape pod which was traveling down to an unknown location near to Beach City.
Season 2[]
In "Joy Ride", her current location and status is unknown, even though her escape pod was discovered crashed in a field by Steven and the Cool Kids.
In "Keeping it Together", Peridot was shown to have left the Escape Pod to experiment on the Cluster (mismatched body parts of gems that died in the war) at Kindergarten in the damaged Facet Five. She was found by the Crystal Gems and later retreats again by using her fingers as a helicopter.
She appears in "Cry for Help", attempting to try and transmit a distress message to Yellow Diamond to send someone to get her off Earth.
In "Friend Ship", she is the main antagonist. The Crystal Gems attempt to capture Peridot but she evades capture once again. They track her down in the Amazon rain forest of South America, unaware that she set multiple traps to kill them. She was going to crush Garnet and Pearl, but the duo made amends and fused into Sardonyx in order to escape. Peridot tried to communicate with Homeworld through a communicator, but is cornered by The Crystal Gems. Peridot then attempts to retreat once again using her helicopter fingers, but is grabbed by Steven and the others. This causes Peridot to escape, at the cost of amputating her left foot. As a result, she vows to get revenge on The Crystal Gems for the loss of her left foot as she flies off into the distance.

Peridot without her Limb Enchancers.
In "Catch and Release", Peridot first appears hidden near to Steven's bed and kidnaps him. She takes him to fix the warp pad to escape from earth since Yellow Diamond and her devices can't help her, but he is no longer able to do such thing. After a little conversation, Peridot was about to reveal her true purpose of her mission until the Crystal Gems warped in. After a battle, Peridot tries to make them realize about what is happening but is finally poofed and bubbled to the Burning Room. Unaware of knowing what she really wanted to tell them, Steven released Peridot from her bubble, but this time without her Limb Enhancers, revealing that she is actually not much taller than Steven. Steven tries to question the frustrated Peridot, but she flicks him and escaped, unaware that all of the Crystal Gems were right above the stairs. Peridot freaks out and runs into the bathroom, while Steven tells the gems why he un-bubbled Peridot and that she is afraid of something called The Cluster. With Peridot refusing to leave the bathroom, the gems decide to leave her there
In "When it Rains", while she is civil with Steven, she refuses to tell the Crystal Gems about the Cluster when they try to interrogate her through the bathroom door. After the Crystal Gems leave on a mission, she panics and runs out of the bathroom at the sound of thunder, assuming the Cluster has finally emerged and that the thunder is the sound of the planet being destroyed. She clings fearfully to Steven whilst he demonstrates the concept of precipitation to her using a saucepan as a means of explaining the thunderous booms. When Steven ventures outside to show her that rain is harmless, she is seemingly concerned for his well-being, although after hesitantly testing the rain herself, she joins him outside. Taking this demonstration to mean that Steven was in fact a more intelligent being than she initially thought, she then agrees to share her information on the Cluster with Steven exclusively, still mistrusting the Crystal Gems. However, all her data was stored in her limb enhancers, but Peridot reveals there is a backup of her logs in the Kindergarten. Steven agrees to accompany her there with the caveat that she hold his hand the entire time. Warping to the Kindergarten, the two of them fall off a nearby ledge as Peridot attempts to use her nonexistent limb-enhancers to scale the wall. Commenting on the lackluster condition of the area, Steven reveals that he is a human-gem hybrid, which puzzles Peridot. At Facet Five, she tells Steven the origins of the Gem Mutants and the threat that the Cluster poses to Earth, but she believed that with Steven's vast knowledge of Earth and its behavior, the two of them can stop the Cluster from emerging. Steven, however, tries to clarify her misunderstanding by telling her that he used to be scared of thunderstorms when he was young but lost his fear when he learned how they work from his dad, and suggests informing the Crystal Gems about the Cluster. However she is still reluctant to involve the Crystal Gems, believing stubbornly that she and Steven can stop it together. At this point they are attacked and cornered by Gem mutants, and quickly saved by the Crystal Gems, who initially berate Steven until Peridot assumes responsibility for the incident, and finally agrees to share information on the Cluster.
In "Back to the Barn", Peridot concedes to her lack of options and, with Steven's help, informs the Crystal Gems about the Homeworld's plan for the Cluster to destroy the Earth. Pearl and Peridot both decide they need to build a drilling machine to reach the Earth's core and prevent the Cluster from reaching its point of emergence. Peridot immediately begins to destroy and cannibalize Steven's various household appliances before Steven suggests that they use the parts in his father's storage barn instead.
Whilst forming plans for the construction of the machine, Peridot reveals the prejudices apparently native to Homeworld Gems regarding the caste system of gem-types, informing Steven that pearls on Homeworld are little more than a form of coveted high-class servants, and that Pearl was "not made" to do anything other than serve her betters. This leading to a more general argument as to who should design the drill, Steven suggests they have a robot building competition to decide who should be in charge. After building their respective robots, Pearl and Peridot begin competing in a series of challenges presided over by Steven. When the competition is over, Steven tallies their scores only to find it is a tie. Pearl deduces that they must share leadership, but Peridot refuses to accept the outcome, repeating her opinion that Pearl was inherently beneath her. Peridot wins the subsequent brawl after smashing Pearl's robot, but not before being punched in the face by a defiant Pearl. Declaring herself the winner, Peridot is confused when Steven and the other Gems still stand behind Pearl, Steven declaring that Pearl is anything but "a common Pearl", because she works hard to learn new skills and better herself. Peridot reluctantly acknowledges Pearl as a competent technician, and subsequently agrees to work with her.
In "Too Far", in order to replace her logbook, which was saved on her limb enhancers, Steven gives Peridot a tape recorder instead to make a record of her experiences. Whilst looking over Pearl's designs for the drill, Peridot asks Garnet to unfuse, as it makes her feel uncomfortable. Unaware that her comment was offensive, Peridot is leashed to a nearby fence in retaliation. Whilst working on a microwave, she becomes increasingly exasperated and bemused by Steven and Amethyst amusing themselves with her lack of knowledge about Earthly objects and customs. At this point, Pearl mentions how they still need a head for the drill, and Peridot suggests they get one from an Injector at the Kindergarten. Garnet tells Steven and Amethyst to chaperon Peridot and keep her in line whilst there. Whilst at the Kindergarten, Peridot vents her exasperation of her current situation. Taking positive reinforcement from Amethyst's laughter at her many roast-like commentaries about the other Crystal Gems, Peridot inadvertently tells Amethyst that she is a defective Gem. Not noticing the danger signs in Amethyst's reactions, she proceeds to explain in detail how Amethyst is "genetically wrong", as she was supposed to come out large and physically imposing, as opposed to small.
Back at the barn, Peridot is confounded by Amethyst's new coldness towards her and reacts in frustration when Steven explains how she had hurt Amethyst's feelings. Confused and hurt by Amethyst cold-shouldering her, Peridot fails to notice a malfunction in the drill head, sending it spinning out of control. When the drill head hurtles towards Amethyst, Peridot rushes to push her out of the way whilst Steven stops the machine. During the cleanup, Peridot records an apology on her tape recorder. She explains that despite being ignorant of Earthly customs, she is trying to learn and that even though Amethyst is defective she, Peridot, is no better due to having failed in her mission and allied herself with the enemy, and struggles with that as well. Amethyst forgives Peridot, albeit with the side-note that she is "still a nerd".
In "It Could've Been Great", when the Crystal Gems go to the moon in order to discover the exact location of the Cluster's gestation, Peridot sees her Diamond's mural and talks about her. Upon discovering the Cluster's coordinates in the Diamond Control Room, Steven inquires about what the Gem empire had originally planned for the Earth, prompting Peridot to bring up a holographic display of a completed Gem colony. While everyone else present is horrified, Peridot describes the hologram with approval, earning the ire of the other Gems. When she inadvertently insults Rose Quartz' memory, Garnet is almost pushed to violence until Steven talks her down, thoroughly confusing Peridot, who does not understand the reaction. Before leaving the room, Peridot covertly aquires a small, diamond-shaped device from the control room throne.
In "Message Received", it is revealed that the object she took was a Diamond Direct Line Communicator to contact Yellow Diamond with. Believing that she is going to use it to summon more Homeworld Gems, Steven locks her in the barn and takes it. Upon telling the other Gems what Peridot did, they were enraged at her, mainly Amethyst. Peridot escapes with Peribot and takes the communicator back. Her robot suit is destroyed and, during the ensuing struggle, Peridot activates the communicator, prompting the others to hide whilst Peridot makes her report. When asked why she did not call from her ship, she lies and claims the ship to have been destroyed because of a mistake upon landing, indicating that she cares about the Crystal Gems to the point where she does not want to rat them out to Yellow Diamond. When informed she will be sent for and go to her next assignment, Peridot quickly gives her opinion that the Cluster should be terminated, saying that the Earth could be of use for its unique resources. Yellow Diamond refuses the gesture and orders her to allow it to grow and destroy Earth, chiding her for her many failures, and making it clear that she wants the Earth destroyed. Upon seeing that Yellow Diamond can not be reasoned out of her decision, Peridot declares that there are things on the Earth worth protecting, screams that she is a clod, and quickly cuts the connection. Horrified at her actions, Peridot curls into a fetal position whilst the Gems dispose of the exploding communicator. The others praise her for her actions, and declare her to be a Crystal Gem.
In "Log Date 7 15 2", Peridot wrestles with her rebellious actions, repeatedly switching between horror and ecstasy as she replays the word "clod" over and over on her recorder. Whilst Garnet sits her down to try and help her cope, Steven decides to listen to Peridot's past logs throughout the time of her being with the Crystal Gems to see how she and Garnet became so close. Beginning with Log Date #7 11 2, Peridot describes being given the tape recorder by Steven, and ponders if the organic lifeforms on Earth (humans) have the ability to fly, having witnessed an insect doing so. In an effort to find out, she pushes Greg off of a roof, only to be remonstrated by Garnet, prompting Peridot to decide that she does not like her. Steven then skips to Log Date #7 12 2.
Season 3[]
In "Super Watermelon Island", Peridot starts evaluating frequent tremors that have been going on, diagnosing them to be related to the upcoming hatch of The Cluster. She fears that it is closer than ever and that the Crystal Gems must take immediate action, and gets annoyed when these go in hunt of Malachite instead, in Mask Island. She stays with Steven and the two discuss the issue of Malachite, before she instigates Steven into connecting with the Gems through his psychic, to help them out.
In "Gem Drill", Peridot witnesses Steven waking up again, as intense earthquakes have hit the ground, and is stressed, commanding Steven to go to the drill immediately, and gets annoyed when the Gems can not come to help. However, she loses no time and starts drilling, with a cold and calculated endeavour all throughout the trip, only opening herself when they hit the layer of hot peridotite and she acknowledges her feelings, or the lack of them, towards Homeworld, before being interrupted by a barrage of Cluster prototypes, which she eliminated using a blast cannon integrated in the drill. They soon come across the Cluster, and while Steven is reluctant to its destruction, she is ready to go for it, if it was not for the fact that it starts forming on the spot and Peridot realizes that they were not able to save the Earth, and shares a "last moment" with Steven. Luckily, the Cluster is confused and struggles to form, opening an opportunity which she uses to make contact with the Cluster. She gets worried when it seems that Steven is not feeling well with the impact and even questions weather she should continue for Steven's sake, but Steven's problem seems to be really serious, as his pain and drastic movement cause the drill to break several times. She is only later seen when Steven wakes up from passing out and is worried for him, and is shocked when he informs her that they will need to bubble the Cluster. Luckily, Steven and the shards take care of the problem, and soon they are on the surface again, celebrating, as the Gems and Lapis Lazuli return from Mask Island.
In "Same Old World", Peridot decides to stay at the barn instead of living at the Temple. When Lapis Lazuli and Steven return to the barn from their trip, Peridot welcomes them back home where she announces to Lapis that she will be staying at the barn which Lapis is not okay with.
In "Barn Mates", Peridot and Steven try to come up with a compromise so that her and Lapis can both live at the barn together. Lapis does not want to stay at the barn because she does not like Peridot whom brought her back to Earth as an informant. Peridot explains to Lapis that she is different, and Steven vouches for Peridot, but Lapis is not convinced. When Lapis leaves the barn to rest on top of the silo, Steven helps Peridot write an apology letter for Lapis. Once it is completed, Peridot calls for Lapis, but Lapis ignores her which makes Peridot wonder why she is not responding. Steven calls for Lapis, and Lapis comes down immediately and Peridot hands her the letter. Lapis reads it out loud and is not thankful about the compliments given by Peridot. Steven and Peridot return to the barn to come up with another plan and they decide to use the hole in the ground from the drill as a pool for Lapis. The two show Lapis and Lapis explains how she is taking a break from water but thanks them for their generosity. When coming up with another plan, Steven tells Peridot that she should give Lapis something that was hers. Peridot likes this idea and wraps up her tape recorder and gives it to Lapis. Lapis crushes it and Peridot asks what Lapis wants and she wants Peridot to leave. Peridot accepts this and walks way, only to return with a Homeworld tracking vessel after her. Lapis destroys it and asks Peridot if she is okay, and Peridot smiles ear to ear because Lapis seems to be okay with her.
In "Hit the Diamond", Peridot panics when she sees the five Ruby soldiers hopping out of the Roaming Eye. Peridot believes that the Rubies are after her since she insulted Yellow Diamond. Peridot is instructed by Steven to stay in the barn while the Gems and the Rubies play baseball. At the end of the game, when the Rubies discover that the Gems are actually Gems and not humans, they fuse together. Peridot crawls out of the barn on all fours and scurries over to the scene like a dog. She pleads the Rubies to take her since the Gems should not be fighting her battle. Peridot is surprised when she discovers that the Rubies are actually looking for Jasper and not her.
In "Earthlings", Peridot with Steven and Amethyst observe hiding behind rocks, Corrupted gems kept by Jasper himself. Peridot is frightened by his former superior and suggests going for reinforcements but Amethys and Steven chose to fight against Jasper while she remains hide. But when Jasper makes comments about Earth being a worthless planet, she timidly comes to its defense. Surprised, Jasper bitterly asks her what is she doing here and Peridot comes out of hiding, shouts to her that she is a Crystal Gem and that she is no longer afraid of her. She tries to use her ferrokinetic powers against Jasper but has trouble activating them. After Jasper is beaten by the fusion of Steven and Amethyst, she furiously asks Peridot how was she able to join them and how can she want to defend this wretched planet. Peridot contradicts it by affirming that the earth is magnificent, that it lives there and that the earth changed her. Jasper refuses this reality, calls the Earth a prison and turns into Corrupted gem and attacks but Peridot answer with his power and stabs Jasper with a metal spike.