Headcanon: Suicide
But when she gets close to attempting it, she stops herself, or rather, something else stops her. She fears as though if she were to actually take her life, that someone would he disappointed in her. And that keeps her away from suicide more than the grief that she could possibly cause someone.
At the heart of it, Charlie is simply too stubborn and too proud to take her own life, searching for other means to do so instead. When she does die, Charlie prefers to go out fighting. Quite literally.

