Well, a great plot for Gears of War Berserker fanfiction could involve a group of soldiers who discover a young Berserker that seems to have some level of intelligence. They try to train it or at least understand it. Another could be set in a post - apocalyptic world where the Berserkers have evolved further and the main character has to figure out their new abilities to survive. And, a third option is a story about a scientist who was involved in creating the Berserkers and now has to face the consequences when one gets loose in his lab.
In Gears of War Berserker fanfiction, you could write a story where a Berserker forms an unexpected bond with a small child. The child is not afraid of it and the Berserker, in turn, protects the child from other threats. Another idea is to have a fanfiction where the technology to control Berserkers is discovered and there is a power struggle over who gets to use it. Also, a story about a group of resistance fighters who use the Berserker's natural instincts against their creators would be quite interesting.
Well, you could have an OC that is a former athlete turned soldier. Their physical abilities could give them an edge in combat, but they also have to deal with the mental toll of the war. They might befriend an old - timer in the Gears of War who teaches them the ropes. Or an OC who is a journalist embedded with the Gears. Their job is to report the truth, but they get caught up in the middle of a conspiracy within the military ranks, and they have to use their wits and the help of their newfound friends in the Gears to expose it.
One idea could be exploring the origin of the Locust in more depth. Maybe there was a scientific experiment gone wrong that led to their creation. Another could be a story where a human and a Locust form an unlikely alliance to fight a common, greater threat within the Gears of War universe.
One interesting idea could be exploring the backstories of the minor characters. For example, the life of a regular Gear soldier before the war, how they were recruited, and their families. Another idea is to create an alternate universe where the Locust and humans form an alliance against a new common enemy. It could change the whole dynamic of the Gears of War world.
A plot idea could involve Kait forming an unlikely alliance. For example, she teams up with a former enemy who has some unique knowledge or ability. This alliance could lead to a series of adventures as they try to stop a new, powerful enemy. Also, a story about Kait's inner struggle with the dark secrets she's uncovered would be engaging. She could be torn between using the knowledge for good or being corrupted by it.
Perhaps they find a lost technology that could change the future of their world. Sam wants to use it for the good of all, but Anya is more cautious. This difference in opinion causes some friction between them at first. But as they face external threats who also want the technology, they learn to work together and reconcile their differences.
For Gears of War 4 crossover fanfiction, a crossover with the Star Wars universe would be really exciting. The Gears' tough and gritty combat style against the backdrop of the Star Wars galaxy. The Jedis and Siths could interact with the Gears in various ways. Maybe the Gears would get involved in a conflict between the Galactic Republic and the Separatists, using their own brand of weaponry and tactics.
One idea could be that the alliance forms due to a common threat from a new, even more powerful enemy. For example, a third alien race arrives on Sera and starts to decimate both human and locust populations. The two groups are forced to put aside their differences and combine their unique combat skills and technologies to fight this new foe.
Another plot could be set in a post - war scenario. Anya and Sam are part of a team rebuilding society. Anya is focused on diplomatic relations and Sam on security. However, they encounter a group that wants to disrupt the peace. Together, they have to use their different approaches to deal with this threat. Anya tries to negotiate while Sam is ready for combat if needed. Their relationship evolves as they navigate this complex situation.
One idea could be to explore the backstories of the minor characters in the Gears of War universe. For example, you could write about how a particular soldier got recruited into the COG. Another idea is to create an alternate timeline where the Locust invasion happened differently. Maybe the COG discovers a new weapon early on and changes the course of the war. You could also focus on the relationships between the characters outside of combat, like how they unwind and deal with the stress of the war.
A cool concept for a Gears of War self - insert fanfiction would be if you were a member of an ancient civilization that has some hidden knowledge about the Locusts. You get rediscovered during the war and use your knowledge to turn the tide. You could also be in a relationship with one of the main characters, like Marcus Fenix, and through that relationship, influence the events of the war in unexpected ways.