Yeah he looks like a yandere but I still want him with Myeongi, I'm sure he'll be treated a lot better.
No, he won't. Heongjae (silver haired guy) is just as bad as Jingi. In later chapters the raws show that Myeong-IL finds out why they're in jail and Heongjae isn't as complacent as you think. When it came to torturing other inmates Jingi and Heongjae were partners in crime and Heongjae was just as brutal as Jingi.
Did he treat Myeongi like Jingi is treating him now in the later chapters?
No he hasn't hit Meong-IL and Jingi is a lot more violent towards Meong-IL but other than that Heongjae hasn't really proven that he won't repeat his past actions. Jingi is more violent, a rapist, and likes to torture people. Heonjae is most likely to molest, kidnap, and torture. We do see him become a bit more possessive towards Meong-IL. Here are the raws if you want to see for yourself: https://toonkor362.com/%EA%B5%90%EB%8F%84%EC%86%8C%EC%9D%98-%EA%B0%9C%EB%93%A4
yeah just cause Heongjae isnt violent towards Myeongi doesnt mean he is a good person. and he lets Jingi do whatever he wants so hes not a victim and should be treated as an agressor/bystander.
guys it gets worse. a lot of you like the other brother but lowkey hes scary too