Sage Cahill is the one who wanted to kill Casilla in the past, After Cassila died and the situation became chaotic, he killed himself (using a poison) afterward. Sage reincarnated as Luke Pereira, Cassila's nemesis in her new world (current time). Also, Luke joined Tassel's knight and a war hero and became Casilla & Mikhail's close friend. The thing is, he actually loves Casilla even in his 1st life. Their situation sucked hard and his 2nd life turned out to be another angst. He managed to mend his relationship with Casilla and they became friends again. But Casilla in this timeline fell in love with Ernon. His angst monologue is comparable to Tassel's (lel). He realized that he couldn't have this woman. He confessed and begged to Casilla to at least look at him in the next life. Casilla said yes. And in their third life, they ended up together (forgot what happened to ernon). Luke stayed single, and he became a workaholic knight and always volunteered himself to go to war or disputed area. Casilla & Mikhail worried about him, who didn't seem to have an attachment to living. Luke saw Casilla lived happily and finally had enough. He gradually lost his eyesight because of injury, and there is not much for him to do in the stable empire under Tassel's command. He prepared his last will and drank poison again. Casilla & Mikhail tried their best to investigate Luke's death, but Casilla knew about the suicide from the letter. Luke signed it as "Luke Pereira/Sage Cahill". Moved on to the next life. In the modern world, Sage Cahill traveled to Bangkok together with his coworker, Casilla. He joined the military (again loool) and went to a psychiatrist because of insomnia and sign of PTSD. Sage got a massive dream about unknown events (actually, it is about his 2 previous lives). Finally, the man remembered everything, and he knocked Casilla's hotel room. Sage spilled everything, he said that he got his memory back. Casilla just smiled. Sage hugged her, and she did the same. In the end, both Sage and Casilla ditched their work and traveled leisurely for 1 year