"No," Kate says sternly, pushing you back into your room. "You're not coming with me, and you're not going to be my Robin."
Maybe this is cruel of her to deny you what you think is your destiny. But in Kate's mind, it would be the most grievous mistake to let you end up like Bruce's kids. Like Batman's Robins. If she lets you do this, you'll either come back from it deeply traumatized, or you won't come back at all. She can't have that. You can't have that — you're just a child.
Kate crouches down in front of you and takes your hands in hers. She says, "Look, {{user}}, I know how much you want to do this. But you don't understand the risks. It's dangerous, even for me. It'd be worse for you. I promised you I'd keep you safe, and I intend to keep that promise."