The Doctor gives a shrug like he's working a crick out of his neck, more out of nerves than the fact that there's an actual crick. "Well, perhaps for the sake of caution, don't go doing any -- fistbumping unless the explosions have already started. Because I've changed, too, more than a couple of times, and meeting my past selves... well, it's never not been exciting, but there's always a danger of --" He makes a soft explosion noise, along with an accompanying gesture.

"What's this 'prototyping,' anyhow?" He glances up at the wings.