I think Sage was blackmailing Chad. And why?
EP1:
Sage finds a red note in Chad's gym bag. She meets the MC who confronts Chad on his first day, who is probably the strongest guy on campus. He even confronts him twice in one day, which Sage witnesses.
Sage and Chad have a heated argument. But Chad can't lose Sage's favor, because Sage probably talked her adoptive father into making Chad president of the Jocks. That way he could protect Troy from the other Jocks, whether Troy was a Jock or not. Troy needed Chad's help in the gym, too. But because of the fight Chad had to calm Sage down again and to distract him he gives Troy a black eye. He takes the guitar away from the MC and gives it to Sage because he knows she always wanted to play guitar. The MC gets it back and learns that Chad stole the guitar. A stolen guitar is not a great gift and Sage gets angry. She asks the MC to find out who Chad is cheating on her with.
EP2:
Sage asks the MC to go to the gym. She lays in wait with binoculars and watches everything. This is also how she sees the MC defending himself against Dawe. Her plan matures. The MC agrees to give her an hour of martial arts training. Nice of him. But Sage wants to get revenge on Chad by losing his presidential title that Sage organized for him. Sage must have some embarrassing dick pics of Chad or other pictures that she can blackmail him with. Sage also easily got the pictures for Dawe. They talk to Quinn, who still had a good relationship with the DIK's at the time, and Arieth, who is after everyone's dick anyway. So the pictures are not the problem yet. But Chad is, and that's what Sage is afraid of. Chad is already violent towards Sage in EP1 and he seems to have no problem raising his hand against girls. Riona writes in a letter that she was beaten, and Chad apologizes. But now Sage has the MC on her side. Is Sage perhaps trying to take advantage of the MC's abilities?
EP3:
Chad gets the pictures and freaks out. The MC fights back and a day later Chad is no longer president of the Alphas.
EP7:
Sage, in the meantime, has become a good friend of the MC. Maybe more, that's up to you. The situation with Chad has calmed down. But there is still a danger that Chad will find out who blackmailed him. So there's a second training session for Sage. She doesn't want the MC to fight her battles anymore.
EP8:
Sage is worried about how to act towards her parents about Maya. She has stood up for someone (Chad) before and was disappointed. It's understandable that she's worried about that. Also, the MC might learn that Sage stood up for Chad and conclude that Sage is behind blackmailing Chad. I think Sage is very scared because the MC sees an ugly side of Sage.
It could be that way, but it doesn't have to be.