Thanks for Asking, I'm Not a Clown [Western Crossover]

I'm an ordinary person living in Gotham. The people here are honest and the city is full of talent, but none of that has anything to do with me. I'm a city dweller who seems completely isolated from the city's crimes. No matter what happens, it never stops me from playing with my little darling. My little darling is my cat. I like to call him Treasure. He's a black cat I found by a trash can. Oh, God, I swear he's the only treasure in my heart. I'll love him forever. I've already decided never to marry anyone, and to spend my life with my treasure. Just as I was about to turn thirty, a man dressed like a bat crashed through my window. In a voice altered by his voice modulator, he said, "Listen, old friend. You know you have to pay Arkham a visit today, right?" Me: "???" Wait, sir, who are you? 1. Not written in first person. I'm a fan of top protagonists, but the "me" in the blurb only has eyes for his cat, so there's no romantic pairing, just Jump-style friendship. 2. Parallel world. A few characters have memories of the main world due to certain experiences. "Me" is this world's Joker, so the Joker from the main world won't appear. Gotham will be a little easier on the big guy, with no tragic backstory. Please take note if that's not your thing. Theme: I just want to tease the big guy, Clark, and the five Robins! [?]