So everything was just a role play?
And Prez haven't had a chance since the beginning?
if they pull an actual twist like that, I would riot hahaha, but no, she gives him shit just because she's jealous, she was gonna complain to him when she would have problems (like how it happened with the literature club), she will throw criticism if needed... at least that's what it felt like how she saved him, she will give the expressions he needed to see from his little bro.
and if we go a little further, what she did was what Asahi would do, in 2 forms: helping him and showing him the emotions, as we saw from ch.19, Miya liked that about Asahi when she confronted her sickness while Sora admired his little bro but would have liked to be blamed or more like has seen more expressions from his little bro as he endured the pain to see everybody smiling, so what Sora needs is pretty much Asahi haha.
and if we go even further beyond, in both cases it would be more admiration for both of them from his feelings about his brother, so that's why the final heroine should be... the chaotic magic senpai. (this last one is a joke though)