I named him Rebound, because the first night in my house he leapt from the couch, bounced off the coffee table, and flew three feet through the air to land by my feet.
I found him by the fire hydrant in my front yard, very young, a little scared, happy to see me. No one in the neighborhood was missing a puppy. His collar was too tight. His paws had no dirt on them, and were as soft as his belly - as if he'd never walked on a hard surface in his life - so I'm pretty sure he was dropped there. (I'm on a corner near a major street.)
He's recovering well. Still has pain around his ribcage and shoulders, but has figured out how to walk on three legs (though only for brief periods - the front leg that works has a cracked scapula, and it tires quickly.)
Last night, he used those springs in his butt to leap onto the couch. The couch is as tall as he is, but he just leaned back and sprung up - landing on his back legs and then letting himself tip forward onto the cushions so he wouldn't impact his front legs...
Looks like one of his legs is completely dead, though - and it will likely have to be amputated.
But he's going to adapt just fine!