While not necessarily abandoned, Gourdy is implied to have had parents at some point and he struggles to remember them. Much of his character revolves around a fear of people forgetting about him and vice-versa, and his twisted counterpart may call out for his parents when transforming into his larger form.
One of the playable characters, Scraps, while technically not a cat is still very visibly catlike and (like all other playable characters) can be killed
A few of the player characters (Shrimpo, Scraps, Pebble, Flutter, Flyte, Cocoa, Eclipse) are based on animals and can be killed in-game. Most are anthropomorphic except for Pebble and Coal
Flutter is a butterfly and can appear as both a playable character and a rare enemy/Twisted. Flyte is also a butterfly, but his Twisted only appears during the Easter event
Twisted Sprout has a few sounds he'll make while roaming the map, one of which sounds as though he is struggling to breathe properly, and another being a single word that sounds as though it's garbled by liquid in his throat.
Goob and Scraps are siblings, Flutter and Flyte are siblings, Connie and Soulvester are twins and Cosmo and Ginger are cousins. Like all other player characters, they can all be killed
There are no intended jumpscares in the game, but given how most Twisteds don't make noise, it is possible for them to appear suddenly and catch you off-guard.
Looey is portrayed as a clown-like character, and currently has two different clown-themed skins available, one of which is called "Creepy Clown", and is loosely based on some horror depictions of clowns.
Not explicitly in a trans way, but some of the dialogue involving Connie (her dialogue with Rodger and some of the gossip dialogue with Gourdy during the Halloween event) has people referring to her by her birth(?) name, the former having her explicitly upset by it
Comso's whole ability revolves around giving one of his hearts to another person, hurting himself in the process as shown by a brief distressed expression and the damage sound effect that plays.
Shrimpo hits his head on machines while completing them, and his twisted counterpart hits himself in the head when he loses aggro.
An audio stinger when a twisted spots you, a barking sound when Twisted Pebble spots you, a buzzing sound when Twisted Vee spots you and a glass shattering noise when either Twisted Rodger is activated or when Twisted Glisten goes berserk (happens either when the last machine is finished or when someone leaves him alone for too long)
There are standees of Dandy on certain maps that appear to be peeking out at the player from somewhere, seeming to imply Dandy watching the player, but nothing concrete or confirmed.