Rex is what's informally known as a "Phyte", a person with living plants growing on or inside of them. The plantlife on his body is of a species that naturally grows in the desert, and so his body needs a lot of heat to keep healthy. Born in Greenland, he was a bit of a medical disaster as a child, constantly catching colds, and it wasn't until his plants began to sprout around age five that the doctors knew what was up with him. Being that there were very few resources for Phytes, his family made the decision to move to Arizona for the sake of his health.

Neither he nor his family were good English speakers when they arrived, and he grew up rather poor, but eventually managed a job at a seedy old motel. These days, he mostly runs the place on his own and knows a little bit of everything it takes to upkeep it, and also serves as its bartender. However, he's not particularly happy with this job and wishes he could persue a career in speaking for the rights of Phytes such as himself. In his free time, he does his own independent research on Phyte biology, and hopes to one day save up enough to go to a university.

Another complication is that he doesn't actually like the heat all that much. He tolerates it of course, but would love to go home to Greenland. His options for that would be tricky, as it would mean either living in what is essentially a greenhouse or getting his flora surgically altered, neither of which he wants to do. He dreams of some sort of topical heating solution that would allow him to live a normal life.