Well, that varies a lot. Different fanfiction writers handle Ben's injuries differently. Some might put him in dangerous situations often, resulting in multiple injuries. Others might focus more on his victories and minimize the harm he takes.
In some fanfictions, Rey might hurt Ben out of self - defense. Maybe she misinterprets his actions as threatening and lashes out three times. For example, in a scenario where she's still learning to trust him, she could mistake his attempts at closeness for aggression.
It could be Vilgax. He's one of Ben's most powerful enemies. Vilgax is always looking for ways to defeat Ben, and he might come up with a new and devious plan to hurt him. Maybe he teams up with other villains to ambush Ben when he's least expecting it.
There are also the possibility of some inter - dimensional beings. In the Ben 10 universe, there are many different dimensions. If a being from another dimension comes through with the intention of causing chaos, they could target Ben. They might have powers that are completely foreign to Ben and his allies, making it difficult for him to defend against them. And let's not forget about the possibility of some of Ben's old enemies teaming up. If they work together, they could come up with a plan to really hurt Ben, whether it's physically or by ruining his reputation among the people he protects.
One possible scenario could be that Ben gets hurt during a fight with a powerful alien. Maybe he underestimates the enemy's strength and gets severely injured while trying to protect someone. Another could be an accident while testing out a new alien form. The transformation might go wrong and cause him physical harm.
The three times Rey hurts Ben can also create a cycle of mistrust. Ben may become more guarded around Rey, and Rey may feel guilty for what she's done. This cycle can be hard to break, and it might take a significant event or a lot of communication to start to repair their relationship. If they don't address the issue, it could potentially lead to a permanent break between them in the fanfiction.
Yes, there are quite a few. You can start by looking on fanfiction websites like Archive of Our Own. Just search for 'Falling Skies Ben Hurt' and you'll find various stories written by different authors. Some might focus on his character development, while others could explore relationships he had within the show.
One popular 'Ben 10 Ben and Gwen fanfiction' could be those that focus on their adventures in different dimensions. For example, there might be a story where they end up in a dimension full of magical creatures and have to use their combined skills to get back home. Another could be about a time when Ben loses his Omnitrix and Gwen has to use her magic to protect them both until he gets it back.
One popular Ben 10 Ben Harem fanfiction could be those that focus on Ben's adventures with his harem while facing new alien threats. For example, a story might have Ben and his harem working together to stop an evil alien warlord from taking over the Earth. They use their combined powers and skills to outwit the enemy.
Another theme might be sacrifice. For example, Ben has to sacrifice something that is important to Gwen for the greater good, and that hurts her. It could be a relationship, an opportunity, or even a physical object that has sentimental value. Often in these stories, the hurt then leads to character growth for both Ben and Gwen as they work through the situation.
One possible scenario could be Ben getting hurt during a battle with a powerful alien. Maybe he underestimates the enemy's strength and gets seriously injured. Another could be that he gets hurt while trying to protect someone, like his grandpa or Gwen. It could also be due to some malfunction of his Omnitrix.