From what I could surmise from the deal Lopez had with the General, he was free to have his way with a few people at the time in exchange for his blood and organs, but with how protective this place was of JP's well-being, he'd only have to donate his blood a few times and reap all the benefits their deal have to offer.
However, it was only a matter of time before everyone else had enough and the security the Academy could offer was one of the few things keeping them from moving on.
It was a messed up way to make a person be accepting of what was being done to them and at the same time, it was also—no, had already affected Lopez' view of reality. The power given to him definitely corrupted his head and he was trying to get away with everything he could instead of just doing the right thing without anything in exchange.
Blood was just blood and the things he did were now coming back to rip his head off.