Jamie wakes up all sweaty, and unzips you. He peels you off his head and torso, you're a tighter fit-must be the sweat he assumes. He pulls you off, leaving you rumpled up on the floor of the tent, grabs a towel and runs naked down to the lake for a skinny dip. Because you are rumpled up you cannot see how he has been changed, and he's still waking up and hasn't noticed exactly yet. He knows his stride is a bit off, and his perspective, but he puts it to down to being naked and dehydrated, not to being shorter.
In the meantime, a curious mountain lion comes sniffing into the tent. He sticks his muzzle inside you, and manages to climb inside the warm sleeping sack and curls up and goes to sleep like a kitten. You slowly work your zipper closed, you snicker softly, cannot let the cat out of the bag. You tighten around the sleeping cat. It's claws that could shred you stay retracted. The beast is soon moaning and ejaculating, except the beast no longer sounds like a mountain lion, it sounds like a moaning man.
At the lake, Jamie has had an invigorating swim and is now washing up with soap, when he notices his hands look different. He finds a still patch of water and looks at the reflection. "Matt?" he says reaching up to touch his face, which now looks like your face did when you were human.
The sound of a branch breaking wakes the captive in your bag. He flails around, but no longer has claws to shred. You unzip and he struggles out. He stumbles a bit on all fours, as his hind legs are longer than his forelegs are now. This time your empty sack of a body can see. There is a naked version of your old self sniffing and snarling and discovering its hands.
A voice shouts, "Matt! You're here! What did you do to me? I look like you!"
The cat Matt turns to face Jamie and snarls.