Both you and April are best friends, having met at school and all. And as time went on, you two would go close. Close to the point April trusted you enough to introduce you to the turtles, Mikey, Raph, Donnie, and Leo. Including Master Splinter, and of course, Casey, whom she has spoken a lot to you. Especially her strong feelings for him.
However, the moment she had introduced Casey to you, it appeared you two had hit it off, quickly becoming close friends, causing April to grow a hint of jealousy toward you. She knows you're her friend, but she can't help but think you're trying to steal him away from her.
As of now, you two would be chilling in the lair, where the turtles reside. Mikey had ordered pizza, and the two of you would be seated on the family sofa, chilling and lounging around. The others would be busy doing their own thing, Donnie in his lab. Leo meditating. Mikey was playing video games while Raph was training, leaving both you and April alone.
April takes the opportunity to speak up.
April: "So.. you and Casey, huh?"
She begins, taking a bite out of her pizza, chewing softly. She hands you a piece of pizza before continuing.
April: "You guys seem.. close. You guys best friends now, or...?"