Hah! Yesss, Ren always wanting what he can't have. Plus I bet Kylo initially thought the cat was Hux's gift to him, he knew the general would crack eventually -- how disappointing, how boring -- but trying to manipulate him through emotional attachment to a pet is a nice touch though. Imagine Kylo reaching with arms out, ready to accept the animal. Imagine Hux gripping Millicent tighter and speed walking the hell away from Ren. Imagine Kylo just staring after him, arms still out, hands curled into fists.

Kylo thinking: So cold! So untouchable! You will be mine!
Hux thinking: DID THAT RIDICULOUS WIZARD JUST TRY TO STEAL MY CAT???