Well, it could be that Nero accidentally breaks some important rule in his world. Maybe he accidentally damages a powerful relic that is crucial for his community's safety, and then he has to face the wrath of the elders or those in charge.
A power - hungry politician in Nero's world could be the main antagonist. They see Nero as a threat to their power or as an easy target to gain more influence. They manipulate situations to make it seem like Nero has done something wrong.
Well, without reading the actual 'nero gets drubk fanfiction', it's hard to say precisely. It could involve Nero's altered state of mind due to being drunk, perhaps leading to some comical situations, or it might be part of a more serious exploration of his character in a fan - made story. Maybe it shows how he interacts with other characters in this drunken state, like his friends or enemies in the fictional world.
Often, Nero can get into trouble when it comes to his own powers. In some fanfictions, his Devil Bringer arm might malfunction or start to have some strange side - effects. This could put him in danger during battles as he might not be able to rely on his usual strength. It could also make him a target for other characters who want to take advantage of his weakened state.
There is a story where Nero's Devil Trigger goes out of control. Instead of helping him in battle, it starts to drain his life force. He has to figure out how to regain control of it while being attacked by a group of demons that sense his weakness. This is a real trouble for him as he's in a double - edged situation.
It might become strained. They could start avoiding each other for a while until they resolve the issue. In some cases, Trish might be less likely to help Nero in his quests or battles if she's really pissed off.
Well, in addition to Mana and Mahad, there could be other supporting characters. For instance, there might be an elder or a teacher figure who is aware of Mana's actions and Mahad's attempts to deal with her trouble. Or perhaps there are other young magic users like Mana who are affected by her getting in trouble, either by getting involved in her mess or by learning from her mistakes.
It could be that she challenged the teacher's theory too forcefully. Hermione is known for her intelligence and eagerness to prove her point, which might not always sit well with some teachers. For example, if the teacher was presenting a more traditional view on a magical concept and Hermione had new, radical ideas based on her extensive reading, the teacher might take it as disrespect.
Maybe in the fanfiction, Nero has made some decisions that go against Trish's beliefs or values. For example, if Nero decides to trust a character that Trish knows is untrustworthy, it could make her angry.