
From what I gathered what happened was they were an orphanage and Mido was a complex kid. Long story short the ML showed Mido kindness and Mido became obsessed with him like he was in love with him. && They became friends. The MC was kind to Mido cause he felt like he would manifest as an omega which he did and he wanted to protect him. Well eventually a man came to adopt Mido and the MC thought he was a creep and just wanted to adopt Mido to do bad things to him. Cause he only came for the omegas and by himself. So they come up with a plan to run away together. He told Mido to meet him at their planned spot. While the MC went to go steal money from the orphanage church he ended up getting caught. The priest asked him what he was doing and MC ended up telling him and asking him why is he trying to send Mido away with a bad guy. The priest who was taken back sat he down and told him that the man was actually a nice guy and was an omega himself and was actually married.And wanted an omega so that they wouldn't have to experience how cruel the world was like them.&& The priest was actually looking out for Mido and wanted him to go to a really good loving home.Something along those lines. MC realize how big of mistake he made ran off to go get Mido && bring him back. Well MC ended up running into some things and got beat up and landed in the hospital unconscious. While Mido was waiting for the MC some thugs came over and bothered him. && Was basically telling him that whoever he was waiting for ain't coming. Since Mido was waiting for a long time. The thugs Sense that he could possibly be an omega. They ended up snatching him up and it's implied that he pretty much got gang raped him. So Mido felt like the MC abandoned him and then with the trauma he got from the rape kinda messed him up since he was such a kid. The police even told him he was at fault cause as an omega he should've never been by himself. It's more to the story but that's basically why he is so upset with the MC.

Yes but he isn't anymore the medication change his trait. That was what a comment had said. The story was translated in another language and I tried my best to decoded it. So I can't say my spoilers are 100% accurate but from what I gathered he did manifest as an omega and took the same medication he gave MC and changed his trait.
I've seen the Season translated in a different language and gotten the jist on what happened to Mido that made him so twisted. It's a mixture of trauma,abuse & misunderstandings. Imma come back once the season is fully translated.