Jubilee was put in charge of a special new version of Generation X that involved mutant youngsters who don't seem like they'll be future X-Men but also aren't the exact type of "mutant ambassadors" that you would like to put out there (as they might not be as sociable or perhaps they have frightening appearances, stuff like that). One of Jubilee's charges was Quentin Quire, who alternates between being a hero and being a villain seemingly every other day. Quire is also super powerful, though, and during a guest spot in The Mighty Thor, he became a host for the Phoenix Force!
Being the jerk that he is, though, it seemed like he would be kicked out of school and he didn't want that, as he would miss his friends. Jubilee promised to help him, but then they were attacked by Jubilee's former Generation X teammate, M, who had been possessed by the energy vampire, Emplate!
Well, in Generation X #86 (by Christina Strain, Amilcar Pinna and Felipe Sobreiro), Quentin realizes that the only way to save Jubilee's life is the use up the last of the remaining Phoenix Force he had in him to turn her back into a mutant!
The series was ending with the next issue, but Strain made sure she went out with a bang (not a fireworks pun, honest!) by bringing the classic Jubilee back! Awesome!
My pal Nevets sort of kind of suggested this one. Okay, folks, there are tons of examples of major changes being made to characters, seemingly "forever," that were then reversed, so feel to write in with suggestions for future editions of this column to firstname.lastname@example.org!