The MC is actually pretty strong, just he's in a sickly body now. He is a loyal servant to the ML before he switched bodies. He was a poor pesant who through a special progam was able to become a place guard. When the origional owner of the body tried to kill himself MC 'rescued' him, but they actually switched bodies. So he is being humble to the ML as he is just a pesant who is not worthy to be that close to the ML. He is guilty over living as the origional owner and no one know that that person is dead. He worries that the ML will treat him as he would a pesant to userpered a concubines place. And, though he dosen't know it because it's not something he will even allow himself to acknowledge, he's in love with the ML. ML is harsh becaue the original owner was flat out evil. He would beat, torture and kill his servants when he was in a bad mood. He would lie to and manipulate the ML every chance he got to keep him away from the other concubines and the empress, though they all get along well. He was constantly picking a fight with and getting an attitude with the other women. Even when he tried to kill himself his last thoughts were that it would make the ML remember him and be sad, not from pure dispare but to punish ML for not loving him only. The thing is that the ML actually was very attracted to him and if he had been a good person he would have easily been able to capture the ML's attention. The MC is a good person and in a body that the ML is attracted to so MC is going to get the love of the ML. He is also chaning the more girly stuff of the origional owner. He started wearing men's clothes, which everyone keeps saying suits him better. He is also going to get a traing sword and start praticing with it to try to build some strength.
I'll tell you if you want to know, but it's a spoiler so don't read on if you don't want it.
The ML isn't really into anyone, he's doing his 'duty' once he falls in love with MC and he stops going to the other concubines. The others concubines actually like the ML, not is a romantic way though, so they are happy for him becasue he found real love. The empress only wanted to be empress,so she's happy. The youngest concubine starts treating MC like a brother because she misses hers and he acts like one toward her so she's happy. The middle one, also comes around to likeing him and being his friend. It's to the point where when the ML does something that they think is mean to MC they all get attitude with ML. I don't know how much of that they will put in the comic it does seem to be hurrying the time line a bit.

Is it worth reading? Don’t like the pussy mc and the ml is too harsh