When Logan was injected with Adamantium and escaped from Stryker's laboratory, he encountered an experimental subject that successfully fused multiple mutant genes. She took him out, and he gave the nameless girl a name.
This is actually the story of a mentally ill patient who continues to cure his schizophrenia.
"I'm mentally ill, not crazy. What annoys you guys who can't tell the difference the most."
"The split personality cannot replace the main personality, otherwise there will be a personality breakdown, and everyone will finish playing together."
"The main personality is the most powerful among us, and even we don't know what she can do."
"Who told you that all the split personalities are in this body?"