For instance, when Dota (Defense of the Ancients) was a Warcraft mod it had a character called "Lina Inverse" that was named after the character from the Slayers anime series, and that three (out of four) of the character's abilities (in the mod) were named after Lina Inverse's abilities in the anime.
Can a novel have a character that has the same name of a anime character (for example) and have the same ability names, or was the Dota case a example of borderline non-infringement?
Character names can't be copyrighted, but they can be trademarked. Traits of a character -- appearance, catchphrases, manner of dress -- all go with 'similarity of a character' and can be elements of copyright infringement.
If this is fan fiction and it will never see the light of day, then there is no issue.
If you want to make money from this work, and if you don't get permission to use the characters that others have created, then you might have an exciting adventure with the tort system of your locality that ends with you paying out lots and lots of money for lawyers, court costs, and damages to injured parties. Woohoo!
