Jaehee (glasses stalker) was prolly the reason why cheol's school life was so shit. They showed him manipulating sangyeol into putting a target on cheol's back, and my guess is that he was tryna make cheol's school life hell so he (stalker) could swoop in and save the day/become his sole source of comfort. The only reason why this play didn't go down was bc minyeong had cheol's back.
I'm guessing this will lead to jaehee tryna uo the ante at college somehow??? And that'll coincide with minyeong outing cheol to his family (which is going to lead to cheol dropping out altogether)

How relevant was he to the plot? I feel like he's an extra character added in and he hadn't done too much towards the plot