Swarm (Gears of War)

""Guys, that sounded like there were dozens of em'. Hundreds. Like a... like a swarm.""

- Delmont Walker to Kait Diaz and JD Fenix, after an attack on their village

The Swarm are the main antagonists of the game Gears of War 4. They are a species of creatures that came to existence over twenty-five years after the Lambent Pandemic. The Swarm is later revealed to be the successors of the Locust Horde. It is still unknown how they became active after the annihilation of the Locust Horde.

Origins
After the events of Gears of War 3, the Locust Horde were rendered extinct after the Imulsion Countermeasure Weapon was deployed. However, they were not actually dead but instead they were covered in impenetrable crystalline shells (after the Imulsion Countermeasure Weapon forced a genetic evolution within them). Unable to dispose of the bodies, the survivors of the COG dumped the cocoons into highly classified locations across Sera, most notably the osmium mine beneath Fort Reval and the gorge beneath Tollen Dam. For twenty-five years there was peace, until shortly before the twenty-fifth anniversary of the end of the Locust War, the Locust began to re-emerge as The Swarm.

Gears of War 4
The presence of the Swarm became active when they started kidnaping COG (Coalition of Ordered Governments) citizens in order to convert them into more members of the Swarm. The Swarm then continued their raid by attacking a village and took everyone except James, Delmont, and Kait (the main characters in the game). They were safe from the Swarm due to being in the generator room and were locked inside by Kait's mother, Reyna, in order to keep them safe (although, consequently, Reyna was kidnapped during the process). Later on, James found a hand that Reyna had cut off from one of the mysterious creatures and takes a chunk of crystal off. Delmont then suggests they go to Marcus Fenix (who was the main character of the previous games and JD's father) for help. The three make their way to Marcus' house, where JD shows him the crystal. Marcus later accompanies them to the osmium mine beneath Fort Reval.

Along the way, the group encounter a strange red biomass and a large group of pods. After discovering the remains of a COG citizen within one pod, the group quickens their pace, only to be attacked by a much larger creature (Snatcher) that abducts Marcus during the confusion. Soon after, JD, Kait and Del find themselves in a frantic battle against Juvies (members of the Swarm) which resemble humans, to much larger versions called Drones that are capable of speech, can wield and use fire arms, and use coordinated tactics. The battle eventually culminates against large predatory creatures called Pouncers.

Later on, deep within the mine, the group discovers a large mass of Locust bodies, still contained within their crystalline pods. However, soon after discovering the pods, the group stumbles across many opened pods, and soon after fight a Scion, a former member of the Locust Horde. It is then revealed that the Swarm are in fact evolved versions of the Locust Horde.

After they fight through the Swarm, they eventually find Marcus trapped in a pod and free him. Marcus tells them that while he was within the pod, he was connected to the Swarm's hive mind network, along with the disturbing revelation that the Locust had never died; they became the Scions, and are now using humans to build an army. Marcus then informs Kait that the Swarm is treating Reyna differently, and that she's being held at another burial site, located nearby at Tollen Dam.

The four then fight their way back to the surface. Marcus suggests taking a detour to get backup from a "friend", but Kait refuses to wait. The squad makes it to the top of the dam, but upon seeing the extent of the second Swarm hive, JD relents and asks if Marcus' friend can help. To contact him, they'll need to reach a radio tower, located in the nearby town of Speyer. They soon encounter a Scion Elite with a missing hand, who is later shown to be the same one who took Reyna. The Scion speaks, saying Reyna is "right where she belongs". They kill the Scion and arrive at Speyer in the morning.

Pushing through the town, Marcus gets in contact with a friend and old acquaintance. Two giant mechs arrive at the agreed rendezvous point. The pilots are to be Damon Baird and Augustus Cole (supporting characters from the previous games). It's revealed that Baird was the one who was spying on JD and provided assistance in the COG settlement. Del, Marcus, Cole, and Baird board a King Raven, piloted by Samantha Byrne, leaving JD and Kait to pilot the mechs. The squad push through heavy Swarm resistance and return to the dam. After the mechs break through the dam and emerge on the dried riverbed where the hive is, a gargantuan Swarm creature erupts from the ground. The mechs and helicopter coordinate to take it down, but the Raven is downed. JD tears off the damaged helicopter's rotary system with the mech and uses it to kill the creature. The Swarm's current status after this is unknown.