If I have well understood the post, the Pluto-Charon system has a kind of atmosphere maintained through the joint effects of the two dwarf planets? Is this correct? It is a bit weird that such a low mass is sufficient to maintain an atmosphere. But I didn't do the maths, so... ;)
Somewhere, I read something about their interaction and the origin of the dark spot on Charon. I do not know if this is completely true :)