He might encounter new and dangerous enemies all by himself. Without the support of the group, he has to rely solely on his own skills and instincts to survive.
Daryl uses his tracking skills. He follows any signs that might lead him back to the group, like footprints or broken branches.
He might lose his control over his own quirk for a while. Since his quirk is erasing others' quirks, if he's hit by a strange quirk, it could disrupt his own quirk's function.
He could find himself in a really tough situation. For example, if he's in the middle of a feud between two magical factions in the fanfiction. He would have to use his wits and skills to try and find a way out or a solution that satisfies both sides. He might also start to question his own beliefs and loyalties as a result of being in this middle position.
In some cases, when Dexter gets caught, the people who catch him might try to rehabilitate him. They could think that there's still some good in him and attempt to change his ways. However, Dexter might resist this change as his nature is deeply ingrained. This could lead to a power struggle between him and those who want to reform him, creating a lot of drama and tension in the fanfiction story.
Maybe he'll go on a rampage in the fanfiction world. He could start using his powerful jutsu to show his anger, like unleashing a Rasengan on the source of his annoyance.
He could use his ninja skills to fight back. Naruto has a wide range of jutsu at his disposal, like the Rasengan. So, he might quickly launch a counter - attack to protect himself.
He might find himself in strange situations that the fanfiction writer has created. For example, he could be stuck in an alternate dimension where the rules of his powers are different. Maybe he's trapped in a world where all his friends have turned against him because of a plot twist in the fanfic.
It could also create a tense situation within the group he belongs to. The others would be worried about him and might split their focus between their ongoing tasks and taking care of Leo. This could lead to some internal conflicts as they try to balance everything. They might argue about the best way to help him or who should stay with him while others continue their mission.
In fanfiction, when Naruto gets called by the council, he might be faced with various challenges. Maybe they will question his loyalty to the village again, despite all he has done. It could also be that they want to assign him a difficult mission that only he can do because of his unique abilities.
She might lose her friends. In fanfiction, when a character like Angelica gets in trouble, it often leads to a strain in relationships. Her friends could start to avoid her, thinking she's a bad influence or too much trouble to be around.