i think one of the things that i havent seen people talk about a lot is this scene
while you could definitely chalk it up to abstraction and Jax's mind being pulled apart i think its definitely more plurality related and Jax is plural
first off, these splits of Jax all have an air of familiarity around each other, they address each other and they all have their alter functions pretty laid out
additionally, maid jax says "how did you get in here" implying that this place has always existed on some level because none of them are particularly startled by Pomni's appearance
maid Jax is Jax's repression of his identity while also serving as a protector (she remains "uncaring" and "ironic" to deflect painful emotions and protect her system)
toon Jax is his need to be the "funny guy" and social alter, he comes around when things are tense and he needs to make a joke to maintain his character type
big eyed Jax fits into either the persecutor or symptom holder role, though he could also be both, hes shown to be the only one angry towards piano Jax (maid jax is exasperated while toon jax doesn't care) knowing what happened with Jax's parents id hazard that he could be a reflection of his father but in terms of being a persecutor we've seen multiple instances where Jax has slipped into this self destructive attitude; pushing people away, causing fights, negative behavior towards himself and others and its always shown with his pupils blown wide
ill be so honest with you, I couldnt initially place piano Jax in any specific role, he acts reminiscent of evil Jax but aside from that we dont see Jax acting like this a lot. but then i started thinking, hes shackled to the piano and initially I thought it was symbolism for being frontstuck but I actually think that its the opposite
when we're first introduced to evil jax hes shy, wants everyone to have a good time, and Jax's first reaction is this
now that we've seen piano Jax my theory is that he was the main host until everything that happened with his mom, this a more vulnerable part that probably was the one that kickstarted everything but because the other splits see him as weak and annoying they keep him locked up in headspace hence why hes chained to the piano AND the reason he would have the key to the room next to him
first off; the fact that one thump makes all three splits mad and piano Jax stop playing is very telling that theres an established presence of these splits prior to abstraction
theyre aware of whoever's behind that door to the point theyve actively suppressed it for quite some time, the way they tell it to shut up and then go back to their poker game shows that its a reoccurring thing between them
but who is behind that door?
well, considering that its heavily borded up in an almost desprate way so no one can go in or out my theory is that its a trauma holder
everytime we see Jax break down he has very specific tells; his eyes get scribbly, he gets tunnel vision, he speaks low and to himself and none of these splits are shown to act like that even piano Jax
but yknow who we see standing next to a red light having flashbacks? the Jax from the next room, this guy
i think hes the Jax they've blocked out, the one who holds all the memories of his real world counterpart trauma and his circus trauma
tldr; i think this scene shows that not only is Jax plural but also the depth of his trauma and repression