The arc that I remembered the most is an ABO plot in ancient China. Host was an omega that was from a poor fishing? village. He was married to his cousin, I think, and was constantly abused. The emperor passed by the village and fell in lust at first sight and made the host his concubine. The host is really beautiful but is not very smart. The emperor dethroned his male empress and replaced him with the host. The host went to the dethroned empress to be trained without realizing the faux pas of doing so. The former male empress felt pity for this idiot host; he doesn't actually hate him. They became friends. At one point, the host saved the former empress' baby and pretended that it was his. The baby (original protagonist?) turned out to be an omega and later masquerades as an alpha. He became the emperor after the old one passed away. The original ML is the younger alpha brother of the O!Protagonist, who lived in the cold palace with the former empress. The two accidentally meet and fell in love. I don't think they actually found out who each other are to each other. They eventually lead a rebellion and kills the host. They believed that the host is an evil gold digger that that caused the former empress to be dethroned. The O!protagonist "died" and became the omega bride of the new emperor, the O!ML. New story line: I don't remember much. I'm pretty sure both sons fell in love with MC. Yes, even the omega O!protagonist. ML is a general who disregards the royal family. He fell in love with MC and constantly sends him books about widows getting remarried. Later on, we found out that the old emperor never died but was just hiding. I don't remember why. He tried to stage a rebellion against the O!protagonist. Again, I don't remember why. I mean he was already the emperor. Why the hell did he fake his death just to rebel against his own son? He never came out in the original storyline either so the host died tragically while in this one he's trying to win back the MC.
https://www.novelupdates.com/series/im-just-this-sue/ raw: http://www.jjwxc.net/onebook.php?novelid=3046784 just put raw title/associated name into google and you can find links to the raw