Maybe they are in a spooky old house and are too scared to sleep alone. So they decide to stay in the same room and end up sleeping together just for comfort and protection from whatever is lurking in the house. This would be a more innocent plot where their relationship as cousins is still respected.
In a situation where they are on a long journey and stop at an inn with very limited accommodation. They have no choice but to share a bed for the night. But throughout the night, they might be bickering about who gets more space or who snores louder, adding a touch of humor to the plot while still maintaining their non - romantic relationship.
They could be on a camping trip and have to share a small tent due to some unforeseen circumstances, like a storm destroying the other tent. So they sleep together just to stay warm and safe.
In most cases, it is inappropriate if it implies romantic or sexual connotations as they are related in the original context. Fanfic should also follow ethical and moral boundaries.
One possible plot could be that Older Ben, having experienced more of the Omnitrix's power and the perils of the universe, takes Younger Gwen under his wing to train her in her magical abilities. They might go on adventures together where Ben uses his alien forms and Gwen uses her magic to fight enemies. Along the way, they develop a deeper bond of friendship and mutual respect.
Well, they could go on adventures where their new - found feelings add an extra layer of tension. For instance, when they're in a dangerous situation, Ben might be more protective of Gwen because of his love for her.
Well, it could be about their adventures in a new world. Maybe they are all in a magical place where they have to work together to solve problems. For example, they might face some mythical creatures and have to use their unique powers to defeat them. Gwen and Gwendolyn could bring their intelligence and magic skills, while Ben uses his alien forms.
Well, one possibility could be that Ben and younger Gwen travel to a time when their family had a big secret. They might discover something about their powers' origin. For example, they could find out that an ancestor was also a wielder of the Omnitrix - like powers, but in a different form. This could lead to a series of adventures where they have to protect this secret from villains who want to use it for evil.
Well, it could be that Ben plays a harmless prank on Gwen while she's sleeping. Maybe he draws a funny mustache on her face or changes her hair into a crazy style just for a laugh.
Perhaps in the fanfic, a strange energy wave hits Bellwood which causes some sort of connection between Ben, Gwen and a group of girls (the harem). Ben is initially confused as to how to handle this new dynamic. Gwen tries to keep everyone in line and focused on protecting the city. As they explore the source of this energy wave, they come across an ancient artifact that seems to be the cause. They must figure out how to reverse its effects while also dealing with their new relationships. There could be some sweet moments between Ben and Gwen as they navigate this new situation with the harem, and some action - packed battles against the guardians of the artifact.
In this fanfic, Ben and Gwen might have various adventures at the resort. They could discover a hidden part of the resort with some strange creatures. Ben might use his alien forms to deal with any problems that arise, like if there's a malfunctioning pool cleaner that turns into a mini - monster. Gwen could use her magic to help keep things in check and maybe they make new friends among the other guests or staff at the resort.
One possible plot could be that Ben and Gwen decide to surprise their family with a homemade lemon cream pie. They search for the best recipe, go to the grocery store to buy the ingredients together. Along the way, they might encounter some minor obstacles like not being able to find fresh lemons. But in the end, they successfully make the pie and their family loves it.
Well, it could be about how Ben and Gwen adjust to their new roles as parents. Maybe they face challenges like protecting the baby from villains who might want to use the baby's special powers (assuming in the fanfic world the baby has some).