Well, it could mean that Chole has the opinion that a fanfiction related to Lucifer involves abuse. Maybe in the fan - created story, there are elements of abuse depicted regarding the character Lucifer.
Sure. It simply means Chole believes there is a fanfiction where Lucifer is involved in an abuse scenario. It could be that the plot of the fanfiction has Lucifer either as the abuser or the victim of abuse.
The phrase'max x chole futanari fanfiction' is quite hard to define precisely given that 'futanari' is not appropriate for general discussion. If we ignore that part and just think about 'Max' and 'Chloe' in fanfiction, they could be characters that a fan has decided to pair up in a fictional story. It could be a story exploring their relationship, their adventures together, or their personalities in a new and different way that the original source might not have shown.
It could be that in the fanfiction, Lucifer has difficulty forming healthy relationships or trusting others. His behavior towards Chloe or other characters might be erratic. Chloe, with her empathetic nature, might think that such behavior is a result of past abuse.
A fanfiction might explore Bell Cranel and Chole in a scenario where they are transported to a different world. They would need to figure out how to get back while also dealing with the new and strange environment. Their friendship could be tested and strengthened during this journey.
You can start by looking on popular fanfiction websites such as Archive of Our Own (AO3). There are often many works dedicated to different characters and pairings, and it's likely you'll find some for Bell Cranel and Chole there.
Stiles' withdrawn behavior could also be a sign. If he used to be outgoing and suddenly becomes very quiet, avoids social interactions, and seems jumpy or nervous all the time. This change in behavior can be an indication that something bad is happening to him at home or elsewhere, which might lead the coach to think he's being abused.
Power is a major theme. Two Lucifers would bring a lot of power into one story, and it can be about who has more power or how they use their power together.
In the world of 'lucifer meets lucifer fanfiction', a common plot could involve a clash of egos. When two such powerful and complex characters meet, there's bound to be conflict. Some stories may also explore a romantic or at least a deeply emotional connection between them, as they are essentially the same being in different forms, and this connection can be both fascinating and disturbing at the same time.