Spoilers for my 70's TMNT AU (and in particular, for the latest chapter of Duck and Cover!)
A lot of these details will be showing up in future stories, but for the sake of filling in the blanks...
Admirers of unusual pets will probably be happy to know that in my 1970s AU Leonardo has a pet crow. He rescued the little idiot (affectionate) when she got her head stuck in a soup can as a fledgling... which is why he named her Campbell.
Campbell, or Cam, for short (and yes, that is an allusion to Cam Clarke!), was injured when Leo found her, and so has only one functional wing. Because of this she can't fly, but she can hop really well, and sometimes awkwardly flutters a few feet up onto tables and chairs, then makes her way from there onto counters and such. She has a habit of taking things from the workshop, infirmary, and kitchen; so when stuff comes up missing from those places, Don, Raph, and Mike generally know to go check Cam's nest in the corner of the dojo. This is really rather like a game to her, and she likes it when they discover what she took from them.
Cam has a complicated relationship with Klunk. She sometimes likes to steal his food, but at other times she will steal food to give to him. Once in a while, she will willingly play the "victim" when Klunk is in a pouncy mood, but he never hurts her. On occasion, they even cuddle together to sleep.
She has learned to mimic a few words, including "hello" and "sensei" and "good girl", and sometimes she gets chatty and just won't stop cawing. She has also learned to mimic Klunk's meows, which seems to confuse the cat. Like wild crows, she has different calls for different situations, including ones that communicate that she is scared or lonely or hungry or just being playful.
When Leo goes out to do his ninja thing, Cam will usually join him, riding in a pouch on his hip or perching on his shoulder. She knows never to make noise when she goes along with him. She isn't much good at helping to steal things or break into places, but sometimes he likes to give her the chance to nab little items while they are out.
I look forward to adding her to future fics, including one that covers exactly when and how Leo found her!