It has been said that imitation is the highest form of flattery, but this is not necessarily true when it comes to the law. All art is to some degree derivative, but where is the line drawn between derivation and theft? Everyone will have drawn Fan Art at some point, as kids if not as adults, we want to draw out favourite characters because we love them. Perhaps we’ll even write stories with them in, because we want more stories, because we want more than what’s already out there. Because we are Fans.
But every time you make Fan Art you are breaching Copyright because you do not own the intellectual property to those characters, concepts or designs. You are not the original artist, nor have they given you permission to copy their work, so you are essentially ‘nicking’ their idea. That’s the letter of the law, but what is the spirit of it? There’s a big difference between lovingly imitating and maliciously stealing.