Yes, it's just a sketch. And yes, it is a crossover as well. But I'm testing this new way of sketching... and I also said some time ago that I will post some Portal stuff. So yeah, here it is. And there will be more coming, because I'm kind of obsessed with this game right now. An when I'm obsessed with something I draw it. A lot.
To think about it... this is actually a ponification of a humanization. With a lot of headcanons involved. It's more fun that way.