Presenting Aurora from the final Marvel Universe series.
Born the mutant Jeanne-Marie Beaubier, she developed a split personality thanks to a strict religious upbringing that condemned her mutant flight/speed powers as demonic.
As a result, the fun loving, flirty adventurer personality that called herself Aurora came to exist and the two personalities: Aurora and the meek-as-a-mouse conservative personality of Jeanne Marie would clash and conflict over the years that she served as a member of Alpha Flight - part of why a lot of people - including myself - loved that series.
Eventually the Aurora personality would win out though she picked up several more personalities along the way.
Originally, Aurora would require physical contact with her twin Brother Northstar to generate light, but during a mission where she was critically injured, she was genetically modified and started being able to manifest light on her own. As a result of that surgery, she also should lose her powers upon contact with Northstar, but that's evolved and now physical contact with her brother allows them to generate light AND heat.