I'm back on that short haired Jean agenda.
I love to see all the fluffy haired Jeans coursing around, but for me he just doesn't look like that. He's had his hair yanked out in clumps, has been probaly held down by it, yanked around by it. So, I think one of the ways he gains a bit of control over himself and his body is by keeping his hair short enough so nobody can properly hold onto it, let alone pull it hard enough that chunks get torn out.
He says he is vain enough that the bald patches it left behind bother him, but i don't think he would go see a hair dresser about it, because letting a stranger touch a part of your body that is connected to a lot of trauma? I don't think he would let that happen.
Cat even pointed out that Jean's hair looks uneven, and she assumes it is like that because he cut it himself. I think he let the patches grow and tried to cut the rest down to the same length, so it doesn't look as obvious as just leaving the rest longer. So I think his hair is quite short, around the lenght hair takes to grow when it regrows for like 2-3 months and the rest of his hair is cut accordingly.
So, besides having short hair being a bit of a self-protective thing, I think, it's also just something that makes sense, because otherwise it would just be SO patchy?