It could be his love interest, like I mentioned before, Lydia. She might reject him because she's too focused on her own goals or perhaps she doesn't see Stiles in that way at the time. Their relationship has always been a bit complex in the show, so this would be a likely scenario in fanfiction.
One possible plot could be that Stiles gets rejected by his long - time crush, Lydia. After the rejection, he might go into a bit of a self - discovery phase. He could start focusing more on his friendships and his own personal growth, realizing that he doesn't need someone else's approval to be happy.
Well, often in these fanfictions, Stiles becomes more confident. His physical appearance might also change, like he could start dressing better or have a new haircut that gives him a 'hot' look. For example, he might start wearing more stylish clothes that show off his personality.
His relationship with his friends would likely become more strained. They might be afraid of him or he might be afraid of hurting them. For example, his best friend Scott, who is also involved in the supernatural world, might be worried about Stiles losing his humanity.
The fanfiction could be about the adventures Stiles and the puppy have. They could go on hikes together in the forest near his town. During these hikes, they might encounter strange things or other supernatural beings. The puppy could either be scared or curiously investigate. Stiles would have to protect the puppy and also figure out how to deal with whatever they come across.
One possible scenario could be that Natsu confesses his love to a character, perhaps Lucy, and she rejects him because she doesn't see him in that way. She might think of him only as a good friend. Another scenario could be that Natsu is rejected in a job or a quest application within the fanfiction world. Maybe the guild he wants to join or the person in charge of a certain task doesn't believe he has the skills or the right attitude.
Well, in a lot of these fanfictions, Stiles can get beat up due to his own recklessness. He might be so determined to solve a mystery or help his friends that he doesn't think about the consequences and ends up in a dangerous situation where he is outnumbered and beaten up. Also, there could be miscommunication. Maybe someone thinks he has done something wrong when he actually hasn't, and they take matters into their own hands and beat him up.
A Border Collie might also be a possibility. These dogs are extremely intelligent. Stiles would have a great time teaching it all kinds of tricks. The Border Collie could also help Stiles in some way, like herding or using its intelligence to solve problems that Stiles might face. It would be a very active and engaging puppy for him.
One great Stiles gets injured fanfiction is 'Healing the Broken'. It shows Stiles getting injured during a battle with a supernatural creature. His friends, especially Derek, are by his side trying to heal him. Another is 'Stiles' Painful Ordeal' where his injury is a result of a mysterious spell gone wrong. The story focuses on how he copes with the pain and recovers with the help of his pack.
Well, in these fanfictions, Stiles' injury can completely shift the plot. Firstly, it can introduce a sense of urgency. The other characters need to find a way to heal him quickly, which can lead them to new places or new characters who might have the cure. Secondly, it can affect the emotional arc of the story. Stiles might become more withdrawn or more determined, depending on how he copes with the injury. This in turn affects how the other characters interact with him and how the overall story progresses. It can also expose hidden strengths or weaknesses in the group as they deal with his injury.