I Became the Younger Sister of a Regretful Obsessive Male Lead

I’ve transmigrated into the world of the BL webtoon where I left my one and only spiteful comment. On top of that, I became the adopted younger sister of my favorite character: the obsessive male lead who is later regretful for his actions, but still dies along with the duke in the end. So, I became determined. Since I transmigrated into this world, I can’t just stand by and watch my favorite character die. Additionally, I also don’t want to die. That’s why, author, I’ll need to change the tags and the ending of this webtoon slightly! From to tragedy to happy ending. “Brother, please smile like that in front of others as well.” I said to Lucian, who doesn’t smile even a little bit in front of others. “…” Was that request too out of the blue? Lucian looked at me with a peculiar expression. “If you do that, I will give you a gift.” I said that because I wanted to help him in any way I could. He looked at me for a bit and hesitated before replying, “A gift… Is anything fine?” “Of course!” The moment I gave that answer with certainty, his expression changed right at once to that of a starving predator… Did I make a mistake? Then, Lucian calmly replied with an expression full of expectation. “Give yourself to me, Rachel.” Huh? What did he say? What did he just ask for?