One possible plot is that there is a power struggle in the Omniverse. Different factions want to control the Omniverse and Gwen 10 gets caught in the middle. She has to decide which side to support, if any, while also dealing with her own personal growth and the new powers she discovers during the war.
The plot could involve Gwen 10 facing off against a powerful new villain who has united all the worst enemies from across the Omniverse. She has to use her various alien forms and strategic thinking to combat this threat.
Perhaps in this fanfiction, the Omniverse War is started by an ancient evil that was sealed away long ago. Gwen 10 discovers that she is the key to stopping it as her unique DNA is related to the origin of the Omniverse. So she travels through different dimensions, gathering allies and knowledge to end the war.
The 'gwen 10 omniverse war fanfic' could potentially revolve around Gwen's role in a large - scale conflict within the Omniverse. It may start with a threat emerging that endangers the stability of the Omniverse. Gwen, being a powerful figure, might be at the forefront of the fight. There could be political intrigue among different species in the Omniverse as well. Some might want to use the war to gain power, while others strive for peace. Gwen would have to navigate through all this while also dealing with her own personal growth and the challenges her powers bring in the context of war.
It could be an alternate version of herself from a dark dimension. This Gwen has turned evil due to some tragic events in her world and wants to conquer the entire Omniverse, seeing the normal Gwen 10 as a threat to her plans.
Most likely Gwen would be one of the main characters, given it's called 'gwen 10'. There could also be other characters from the Ben 10 Omniverse like Ben or some of the alien species.
One popular plot twist is when Ben and Gwen end up in a different dimension where their roles are reversed. So, Gwen has something like the Omnitrix and Ben has to rely on his wits and basic combat skills without alien forms. This forces them to adapt in new ways and understand each other's struggles better.
It could be a story where Merlin and Gwen attend a royal ball. Merlin, who is usually shy about his dancing skills, decides to ask Gwen for a dance. As they dance, they share a special moment and start to realize their feelings for each other more deeply.
Well, perhaps Kevin kidnaps Gwen because he wants to use her as a bargaining chip against Ben. He might think that by having Gwen in his control, he can force Ben to give up the Omnitrix or something valuable. Another possibility is that Kevin has some sort of grudge against Gwen specifically, maybe related to her magical powers that he either fears or envies.
One possible plot could be that they face challenges in their relationship due to the unexpected pregnancy. They might struggle with how to balance their superhero duties and preparing for a new life. For example, they could worry about protecting their unborn child from their enemies.
One possible plot could be that Spider Gwen discovers she's pregnant while still trying to balance her life as a superhero. She might struggle with how to protect her unborn child while still fighting crime.
Maybe in the fanfiction, Esther gets into trouble while exploring a dangerous part of the Omniverse. Ben discovers her plight and decides to rescue her. As he does, they find themselves in a situation where they are trapped and have to rely on each other to escape. During this time, they share their hopes, dreams, and fears. Ben realizes that Esther is more than just a friend, and Esther sees Ben in a new light. Their relationship blossoms from there, with them having adventures together and supporting each other in the Omniverse.
The plot could involve Benhypno trying to adapt to human society. Maybe he has to go to school and deal with normal teenage problems while hiding his true identity. He could struggle with making friends at first because of his unique background, but then gradually learn to fit in and use his powers in secret to help those in need.