Warning: spoilers for Way of X #2 by Si Spurrier, Bob Quinn, Java Tartaglia, VC's Clayton Cowles, and Tom Muller are ahead.
Nightcrawler is one of the X-Men's most recognizable members because of his distinctive appearance. With his blue skin, tail, yellow eyes, and three fingered hands and feet, Nightcrawler has never had the luxury of blending in with larger society. And while his teammates know him as Kurt Wagner, the origins of his name have just been revealed in Way of X #2 (written by Si Spurrier, art by Bob Quinn, colors by Java Tartaglia, letters by VC's Clayton Cowles, and design by Tom Muller).
While Nightcrawler and his codename were introduced in Marvel Comics in Giant Size X-Men #1 (written by Len Wein, art by Dave Cockrum, color by Glynis Wein, and letters by John Costanza), a new explanation from Way of X #2 offers a more compelling backstory. When he discovers that the organization, Orchis, is using Legion (David Haller) and his brain to model the collapse of Krakoan society, Legion suggests that someone kill him so the simulation can end. Nightcrawler volunteers to take his life for him, and though Pixie tries to intervene, Nightcrawler remains undeterred, citing that it would give David a fresh start from the bad reputation he has as Legion. That is when he reveals that Nightcrawler was a name he was taunted with as a child, due to the fact that a nightcrawler is a type of worm. He later reclaimed it as his own, allowing him to break away from its previous negative connotation.
As a character, Nightcrawler has always had to contend with the fact that he looks like a monster to many people. This exchange he has with Legion reflects not only his characteristic sense of empathy and compassion, but also an understanding of how mutants' experiences are shaped by prejudice. By incorporating this into his persona as a superhero, Nightcrawler embodies the best attributes about the X-Men. He finds heroism in the aspects about himself that society is most repulsed by, making him an important model for mutants everywhere.
Here, Nightcrawler's compassion allows him to commiserate with Legion's position, going as far to compromise his own Catholic beliefs by killing him. Indeed, Legion has a reputation in Marvel Comics as a loose cannon, given that he is an Omega-level mutant with multiple personalities and near limitless power. Nightcrawler recognizes how mutants like Legion can be seen only for the destructive potential of their powers, and he implores them to look beyond this perspective.
Yes, the name Nightcrawler originally began as a way to belittle Kurt Wagner as a child, but he has since used it as a way to self-determine the kind of person he wants to be in the world. This particular trajectory is relevant for mutants like Legion, who are looked at warily by both human and mutant society due to the strength of their powers. If any lesson can be learned from the origin of Nightcrawler's name, it is that prejudiced names do not determine the type of heroes that mutants can be.