If your first thought at seeing your younger brother taking care of the 13-yr old star he's in charge of as a manager is "But would they make a good couple?" there's something wrong with you. Like, sure let's say 10 years pass, and the two haven't been working together for a while, they might get together if they get along.
But if he's 23+ and she's 13 right now, if he's taking on the role of a parental figure or reliable older sibling, why would you start fantasizing about this and start playing wing(wo)man? Is the concept of grooming completely foreign to this person? I really hope this is not going to be another one of those male-lead-is-the-only-one-who-sees-a-problem-in-dating-a-minor-but-he-can't-explain-why-meanwhilst-everyone-else-is-like-"Why-not?" kinda series.