To live in a stranger's skin means to see the world from another's viewpoint, to pretend to be something you are not. Like his new 'family,' Xlack is a Magni hybrid destined to protect worlds and weaker beings, but that is one of the very few things he has in common with them. Convincing the leaders that he belongs here is difficult when his adoptive siblings are brats. On top of all that, a discoloration has appeared on his skin. It's growing, but no one else can see it.