You're very valid I campaign for Rintarou being a loser all the time! Also I think he tried a bit too hard when he arrived but eventually, he felt so comfortable around the rest of Inarizaki, he stopped. It wasn't even a conscious move, he just grew into the teenager he is who likes to goof around with the twins and Gin (or film them goofing around). He's got things to prove when it comes to volleyball, and he tries harder than people who don't know him think he does, but when it comes to being himself out of the court, I think he abandons all pretense after a few months. He's got an aura anyway, which is pretty silly but it's the result of him keeping to himself mostly when he's not around his close circle. So, in the end he kinda achieve without trying what he wanted when he was younger. But every time someone gets close enough, they see the real him and it's for the best. Also love him having braces omg, I also think he wears chipped nail polish and tries stuff with eyeliner and khol pens a lot and the twins sometimes show up with hideous makeup as well to make him feel comfy trying his own stuff and not be alone. They even got a stern talk down by a teacher once when they all showed up with something too significant. But the twins stuck with Rin all the way and got grounded with him without saying a word.