The X-Men are known for being loners, at least when compared to the other hero teams in the Marvel Universe. The mutants are often left isolated as they battle against alien armies, gigantic genocidal sentinels, and cults dedicated to purging them from existence. Oftentimes, they are even left to fight their fellow superheroes, given how often the X-Men are at odds with them.
Source：https://www.cbr.com/x-men-team-up-comics-ranked/
