[Papyrus's cheekbones go pink at the idea. That maybe his admiration of Mettaton had been the deciding factor, between having a liquid body he struggled to move around with, or a metal body (that needs just as much cleaning, in all honesty, with how grit accumulates in parts) that he can customize and make cooler and more handsome...!

He's the most flustered about their thoughts and feelings leaking he's been yet, and it's just as well Sans's thoughts shift and give him something besides his crush to think about. Growing wings and bleeding from scars, and other things relevant to death... He makes the sound of clearing one's throat, and nods very seriously.]

My skull lasted the longest... Both times.

[Probably not a coincidence, any more than his brother's scar is. So if it's a mix of remnants from death, and things they admire...]

Wings... not very space-like. But good for getting to space, in other circumstances...?

[Obviously, they don't know how high Sans could fly, if it weren't for the weirdness in the air. And he doesn't know how high birds normally can fly. But there's plenty of science literature indicating that a few humans have been in space, and they need things like breathing, and keeping various body parts in a narrow safe pressure range, and all.]