FL is a transmigrator but it isn't mentioned much, it's only referred to when she thinks about the OG story which is rare. ML and FL first meet when she finds a snake in a bag (someone captured it since the world has a superstition about snakes being evil) and she releases it. ML was the snake since he has a curse that turns him into one. I think they later meet at a party and he defends her and her son of a-b*tch brother after he accidentally breaks a really valuable piece of jewellery. Things progress and he later pretends to have his foot injured so he can have her work for him (she accidentally stepped on his foot with her heels and felt guilty). Whilst she's working for him, he basically feeds her a lot and treats her like a princess. He's already in love at this point but it's ambiguous for FL. But I think she did love him then. I don't know which came first, but she learns of his curse one day when she's visiting his room and finds a snake there instead. They find out that she can stop his curse. And she also slept with him when they were sleeping in the same bed. Everything was completely consensual since he asked before they actually did it. She resolves herself to cure his curse so she goes looking around and finds the OG FL who becomes her friend quickly. Also, OG ML (2nd ML) visits ML one day and it turns out she can also help 2nd ML with his burning pain (also a curse). At some point, 2nd ML kidnaps her but she gets away.

Also, extra info: ML was also the OG Villain. Although FL was scared of him in the beginning, she quickly realised that he was a kind person who wasn't evil. Also, as I mentioned earlier, 2nd ML kidnapped FL. He was obsessed with her but I didn't really focus on this part. Although he is and obsessed kidnapper, he genuinely cares for her and wishes for her happiness. OG FL isn't mentioned much in the story but she does have a major role. FL's f*cking brother may seem only a bit annoying at the beginning but he quickly becomes insufferable when he tries find out about the ML's curse and also tries to sell (+steal) the ML's pills which stop him from transforming. He frequently causes problems and he's the only reason things weren't completely perfect. FL is a kind MC who cares for everyone and loves ML purely.

Back to story, at some point, FL meets a dragon who introduces himself as the subordinate of the most powerful dragon (Sigried but we'll call him S). He helps FL a lot of times along the way and also interrupts ML and FL just when they're about to get intimate. Later, a big battle happens and the truth is found. ML and 2nd ML no longer have the curse and FL gets married to ML.

Turns out ML and 2nd ML are reincarnations of S' children, who were jealous of each other. They had so much resentment against each other that it haunted them as they reincarnated. ML was a half-dragon but S cursed him, thinking that ML did something against 2nd ML and ML had his limbs and wings taken away. The dragon subordinate turns out to be S himself.

FL's brother gets an invisibility cloak and goes to the Duchy to see what's happening. He almost dies since ML goes berserk on lunar moons (I think). After the battle, ML turns into a human and FL runs to him. However, FL's brother is scared. So he gets a bow and aims it at ML thinking that ML is gonna attack them. FL tries to calm him down and it works until ML speaks, FL's brother loses it and lets go of the arrow. FL runs into it and almost dies but ML and 2nd ML decide to get S' heart (getting the heart gives them the ability to have one wish). ML and 2nd ML are transported to their version of an ideal world but without FL. They quickly realise and escape. ML meets himself (pre-reincarnation) and decides that the world wouldn't matter without FL. 2nd ML gives his wish to ML so they can get FL back even if ML would still turn into a snake. However, S decides to give up his life so ML can become a dragon again. FL comes back to life and visits her brother at the monastery he went to. He hoped she'd died. So they left him to serve there forever. Then everything goes as mentioned. They get married.