Responses
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no wait that's bullshit, they were just genuinely asking and questioning ur "comeback" that obviously doesn't make any sense. in essence, you said sth dumb and don't want anyone to call you out on it. also they weren't arguing nor looking for an argument with you so don't accuse others of shit just to make your point more valid
It's not a big age gap in terms of years, but there is still a big gap here. High school is a very closed, insulated world compared to life after high school. I'll do the obligatory #notallteens in case people really need it, obviously there are exceptions, but the fact of the matter is that most high school teenagers are still much more like kids than they are like adults. This MC is one of them, although he is a lovely, responsible, kind older brother. And that's totally normal! It's not a criticism of him or of teenagers. On the other side, yeah some people in their early 20s are still way more like teens than they are like adults. But that's not the way this older guy is portrayed. As others have commented, he's being portrayed as mature and experienced.
I understand teens being interested in adults, that makes total sense since they're finding their way into adulthood. But adults being into high school teenagers is iffy at BEST.
If we get the story switched to be from the older guy's perspective, and it turns out he's actually desperately acting mature after having his sibling's kid suddenly left with him and HE'S also just trying to play the cool, mature adult, then things might feel more balanced. But as it is now, there's an imbalance in maturity, experience and therefore power in the relationship, and that doesn't sit quite comfortably no matter how cute it is.