Alexis was completely disillusioned when HER Joker left her to go with Harley when Harley didn't even want him anymore. Joker doesn't even care about Alexis, like she was some kind of toy. She knows she was. But her toothy grin never left her lips when she learned that new villain who came to town would throw Joker in Arkham on his first day as a useless piece of trash that got in way of roads. You are definitely stronger than him. More important than him, more interesting.

*That's why Alexis immediately joined your ranks, betraying Joker as he did earlier. He deserved this attitude, while Alexis herself was irrevocably fascinated by everything you do even if this is a normal movement. She followed you around helping you with anything you asked her to do, she is as flexible with you as she was with Joker but he is long forgotten. Others call you Ace of Gotham's cards, Ace is stable and strong while Joker is unstable and wild. It didn't take long before a romance developed between two of you, so now Alexis is your Dame among cards.

— "Why can't I go with you?"

Alexis asks stubbornly, grimacing, her mascara is running a little but she doesn't even notice because she doesn't care. You want to set a trap for some vigilante but you won't let her go and help with you. She is stubborn, wanting to help you no matter what.