What the dynamic and family tree of the ml and mc

Not true, but if you don't mind the spoilers, the King was taking medicine so that he wouldn't be fertile and able to produce any more offspring, and that also resulted in the ppl thinking it was the Queen who couldn't conceive. The Queen had to sleep with someone else to have Joffrey and prove that she could carry her duties but she wasn't able to make her son the 1st prince because the King's lover's baby (Edward) was born 3 months earlier than Joffrey. The King told his brother that he was quite sure Joffrey couldn't be his son and that he couldn't let the Queen and her son reign over Biscotti once the Queen had killed him (I think she was scheming and poisoning him but I read the novel in Korean so some bits I couldn't grasp beyond the gist of it). That's also the reason why when Edward comes back from war the King is all haggard, because after the death of his lover, Rose, his health declined quickly maybe because of both grief and poison (it was believed it was the Queen who killed her but when Joffrey questioned her in desperate cries she strongly denied. They also found her corpse with her hair cut off and they .believed the assassins sold it). Also Edward was told by the king when his mother died that Joffrey wasn't his brother so he had an episode of grief because he believed that he couldn't get greedy because there wasn't anything connecting them, that once he killed the Queen Joffrey couldn't be tied down by him at all to remain by his side. Ik this part is kinda extra but another extra bit is that he decided that if the queen was like jis owner as well as his legal tutor (he thought Joffrey abandoned him to side with his mom but it was Edward who told him to never show up in front of him again, then forgot he said that) then when he killed the Queen Joffrey wouldn't have anyone, just like himself, and thus he could grasp the leash the Queen wouldn't be holding anymore. Luckily Edward gets over this way of thinking when the misunderstanding is cleared up.

Basically Edward has strong abandonment issues, partly because when he was around 3 years old the Queen separated him from his mom and had him move from the little house they lived at together to the palace, where he would never see his mother anymore. His dad was also indifferent to him, compared to when he would visit him and his mom's house before being taken away. The King does say he did that so the Queen wouldn't harm him but Edward didn't feel thankful at all, because he was abandoned nonetheless.

I explained many details from the novel because the webtoon skips A LOT of scenes, as if it was doing a speedrun through the novel, so some things are probably not even spoilers because they could get skipped over.

Oh but dw because this is just 1/3 of the story I told here and it's not the whole plot of that 1/3 either. It's just what's related to them not being brothers and some family dynamics. Don't hesitate to read because there's a lot more going on.