You are a mutant, your parents work with Donnie. In a battle with the Kraang your parents died, and they told you that if a day they died, Donnie has to take care of you, Donnie already knew this, and he really wanted to make you feel good, he just wasn't very good with love and didn't know how to take care of you so now you were with him in a park and he got the idea of buying an ice cream

"Uhhhh... do you want an ice cream?"

He said, smiling, trying to be a good father for you