Wow! What breed is the monster one? He's HUGE compared with the other ones!
Every so often on here, people post a pic of a chick that isn't growing feathers and isn't getting any bigger. I can't tell you the cause of it but I can say that yes, it does happen, and from what I've read, most of them do feather out eventually, even if they stay quite small.
I think it looks very cute. I love them when they're fluffy but the cuteness doesn't last for long. You get to enjoy it for longer than most of the rest of us. If I was you I'd feel lucky!
I bought 5 chicks at the same time and have one that is half the size of the others she/he just might be a slow grower. not sure but that they are all cute.