What Do I Do? I Transmigrated as the Curse King's Girlfriend, but I'm a Brain-Obsessed Superfan

I always thought I was an ordinary person. It wasn't until my childhood sweetheart and boyfriend tried to murder me, and I recalled my memories from a previous life as I lay dying, that I realized everything around me was part of a comic's plot. Not only would my boyfriend go on to become the leader of a cult and launch terrorist attacks, but after his death, his body would be taken over by the villainous mastermind, Brain. But that's not the point. The point is... As luck would have it, I'm Brain's biggest fan. So here's the situation: My ex-boyfriend, who wants me dead, is confidently preparing to build his religious empire, while my beloved Brain is still hiding somewhere in the world, waiting for a chance to take over my ex-boyfriend's body. So here's the question... Which side should I help? When I saw my ex-boyfriend with a line of stitches across his forehead, making it obvious that someone else had taken over his body, I excitedly went up to him and clasped his hand tightly. "Actually, I'm a fan of yours." Brain: "?" My ex-boyfriend, in spirit form: "?" Theme: Waiting won't get you anywhere. Only taking action brings hope.