Blue, Grey, and Black in Joker's third semester outfits
Joker's signature colors are red and black. Mostly red, since majority of the phantom thieves have black in their outfits, so it's not unique to him the way red is (excluding Sumire, who emulated his outfit because she admires him). And yet his two 3rd semester-exclusive outfits are highlighted by blue, grey, and black instead.
The black coat he's wearing in the left image is part of his school uniform (other Thieves wear it too), so his only personal touch to that fit is the blue scarf. There is black in the right image, but the main focus is the grey coat.
This isn't unusual. Most of his casual outfits throughout the game skew black and white, but they regularly feature grey and blue. Example: his swimming trunks are blue, his post-interrogation room hoodie was grey. Despite red being Joker's signature color and prominent in his persona aka the manifestation of his soul, it's almost completely absent in his actual wardrobe. In the real world, he opts for blue and grey in combination with his typical black and white. Edit: it was brought up twice in the replies/reblogs that he might just avoid red because he doesn't wanna stand out in school, but his casual outfits also lack red in P5 Strikers despite no longer being in Tokyo so I'm inclined to think that's not the reason for the absence of red.
Red and black is what he IS and what he GETS. Blue, grey, black is what he WANTS and CHOOSES.
You know who does have blue, grey, and black as his signature colors in the metaverse?
This brings us back to the 3rd semester outfits. The Phantom Thieves' winter outfits all feature their signature colors EXCEPT for Joker. Futaba is associated with green so she gets a green hoodie, Ryuji gets a bit of yellow and red, Akechi gets brown (the color of his phone profile), even human Morgana kept his yellow collar.
And if you wanna get annoyingly observant, even Joker's shoes are brown (again, another Akechi signature color). It's not just that Joker wears Akechi's colors a lot, but he is specifically the odd one out when it comes to the third semester.
Remember that these are only available in the false world. In reality, Joker would be in jail. He was never meant to wear these outfits, even if he owned them already. They're an illusion, merely an indication of what he would choose to wear IF he were free to do so.
So omitting his signature red yet again and specifically choosing Akechi's color scheme for Joker's winter outfits has implications. He rejects his 'red' within the false reality, instead wearing the colors of a boy who may not even be alive anymore outside of it. The contrast between what Joker wants, what he personally resonates with, and what he is never allowed to have versus who Joker has to be, something he didn't wish for, something he wants to reject but has to accept.
I don't even know if it was intentional, but the symbolism goes crazy. In the coldest and loneliest winter he's ever felt, Joker chose to wrap himself in the colors of his rival. It was never real, and he had to choose the truth in the end, but he wanted it anyway.
