i'm terrified that I'll be the catch of the night

pre-canon ANP (or “host”) is an emotional part that holds most of the anxiety and depression, especially things surrounding familial trauma (parents divorce, asriel leaving, isolation from school peers, etc) and has most of the self destructive tendencies. They split at some point during therapy. They’re the one that accepted “the deal”. Playing the piano is pretty much the only thing they enjoy doing. Doesn’t like Asriel (bc they’re bitter) or Susie (bc she was mean to them) or Noelle (extreme guilt) very much.

canon > post-canon ANP split when making the deal and developed as their own self during canon (oops), at least in normal route they’re closest to their friends and genuinely try to get better (with Player influence too). They aren’t really aware of other parts and in making fountains memories leak through and are just as confusing to them as us. However, they know the Player and other characters the best. Aside from major traumas they remember most things but just think they have a “bad memory”.

child alter that formed after fusion of various younger fragments. they’re the “prankster” that’s mainly focused on having fun and not worrying about things like emotions or feeling sad. their fixation with playing and sharp objects tends to trigger them to front at the worst times (or best, bc it makes them stop doing “bad things”). However, when upset they can become very intimidating to other parts and take control easily. Very carefree and upbeat but can come across as apathetic or uncaring, and the part that would get in trouble for acting out.

dog alter that formed from trauma around not being treated like a human/person and wanting to be a pet or treated like one. they don’t talk (much) aside from typical dog noises but can think and speak just fine if they really wanted to. they act as sort of an emotional protector when any alter is feeling stressed, or as a protector from perceived external threats. They mostly stay co-con with someone else rather than fronting alone.

monster alter that formed a little bit post-adoption (something like an asriel introject) as they started being aware that they didn’t fit into monster society. they’re the one that can handle basic everyday tasks like socializing with others and going to school or church. they resemble asgore and asriel, maintaining an optimistic persistence and general calm attitude while being responsible and organized. they get bad dysmorphia when noticing that they’re actually human, and their social battery is very low, though. they only front when necessary and then have to take a break for like a week afterwards. They also really enjoy playing the piano.

gatekeeper is like 99% inside-only part that keeps the most memories and keeps the system internally organized. they’re the alter whose appearance has changed the most over time but maintain the most cohesive self. canon> post-canon they look like their dark world self/ Angel who’s vaguely older and taller. They act like an “older brother” to the other parts and think they know what’s best. They only front when no one else can or the system as a whole feels very threatened.