Cerise was part of Lilandra's (head of the Shi'ar Empire) forces when she discovered that her captain used the spaceship for slavery. The only way to finish out that trade was to destroy it, but she was blamed for treason and had to escape to Earth, where she joined Excalibur (of course, she materialized in the lighthouse! Why had she to be an exception?) Some time later, The Starjammers found her and she was brought to a prison-planet where some criminals had been paid for killing her. That gave Lilandra something to think of, deciding to reconsider the whole thing, but till the trial, she's been held in prison.