We know little about the void.
Looking at the way they behave and all the talk about consuming, I think it is highly possible that void creatures are permanently fighting each other there. To evolve and grow stronger. Truly a place of the principle "the fittest survives".
And now imagine that one of these creatures developed a symbiotic lifestyle. Weak on its own, but able to enhance the abilities of a host and all that creature demands for that service is getting some food shared.
Maybe she encountered that creature. And it isn't betrayal to itss species, since these creatures are naturally fighting each other. She was just a possible host for that creature and it probably doesn't even have to share alot of the "battle reward". It gets to consume all these tasty voidling and all it has to provide for that girl is life support.
This is one possibility how this could work.