Off the top of my head:
- Ausars in general (Petplay scenes)
They have been sort of canonically The PetPlay Species (it's in their codex entry!): off the top of my head, Erra, Anno, and Kaede have some petplay scenes, and Erra's are the most well-fleshed-out, since it's Her Big Kink. To unlock all her scenes, you need a flesh-and-blood cock that'll fit (I think??), but you can also use a hardlight for a couple, and there's random Erra/Anno and Anno/Kaede petplay scenes you can get. Stella (Tavros) and Syri have petplay scenes, too!
- Uplifted!Pexiga (With Yammi as crewmember) (Petplay scenes? Commission possibility)
If you've uplifted the Pexiga through the bimbo route (the only one available thus far), then she either has some petplay scenes already or would be well-suited for it (I haven't uplifted her yet, but she starts out as a potential crewmember's pet, and her uplifted form still has all those pet accessories, it seems)!
- Gil (Tavros) (Commission possibility)
Gil (requires very specific circumstances to unlock) would be a good Sub Pet from what I know of him (he, like Erra, needs a flesh-and-blood cock to get all his scenes, though a hardlight'll do you just fine for some of them).
Actually, most of these scenes involve the player's being The Owner and The Dom/me rather than the Pet and Sub - if you're playing a Sub Pet character, there's fewer options, I think, but a lot of good commission possibilities:
- Sera (Tavros) (Commission possibility)
Sera...has? some petplay type scenes? But she's not everyone's type, and they're not full-on, actual petplay.
- New Texas Folks (Commission possibility)
Same with most of the folks on New Texas: there's some playful mooing and being called a "cow" or a "bull," but I don't remember any outright petplay, and cattle tend not to be everyone's cup of tea for petplay. If you're playing a feminine character with a vagina, there's Ciaran, who I think is well-suited for the more niche Dom Pet role (as in, he's the dog and your character's the human (...in a manner of speaking), but he doms your character - so it'd be more like your character would be the "human" pet).
- Fyn (Tavros) (Commission possibility)
Fyn, I think, would be a good Dom to commission scenes for: he's more of the gentle Dom type who is down for any variety of stuff.
- Luca (Canadia Station) (Commission possibility)
She doesn't have any petplay scenes that I know of, but she might be a good canditate for a Domme Owner who gets rough and has some lovely aftercare scenes. She's got some baggage, though, and you run the risk of getting cum-addicted. You also need to keep an eye on some meters to strike a balance between unlocking content and staying away from a bad end.
- Ardia (Zheng Shi initially, potential crew member) (Commission possibility)
Ardia has the same issue with regards to cum addiction and balancing meters; you can get an antidote from Anno, but that locks certain scenes forever. On the bright side, no bad end! On the not-bright side, permanent cum addiction possible. Domme who gets rough.
- Belle (Uveto Station) (Petplay scenes)
On Uveto, if you put on a metal collar that's lying around on the station, you get into some noncon/dubcon petplay and unlock a character called Belle, who is a Domme Owner. It's got a lot of mind control content, and you get a permanent barcode tattoo on your character's ass, but that might be up your alley.
- Vark (Uveto) (Petplay scenes?)
It's been a while since I've interacted with Vark, but I think he has some petplay scenes as a Dom Owner. High potential for a bad end.
- Vava Groom (Uveto Station) (???)
Not fully finished, but promising! It's a pet training/grooming place.
As for who to commission, I'm not sure! If you like a particular writing style as you play through the game, check who wrote it and ask them. I know William has a lot on his plate currently, as do The Observer, Savin, and Wsan (the latter three are working on CoC2 as well right now), but they might still be accepting commissions - I don't know off the top of my head (the latter three are not accepting commissions - thanks for the clarification, Savin!). B isn't accepting commissions at the moment, I believe.
Personally, I play Sub characters, so I'm biased towards that and have more thoughts on who'd be good Dom/me and my opinion's a bit unbalanced in that regard! Hope this helps some, though!