[Well, he's not wrong about Rex being desperate. Not that he's going to admit it.

For a moment, he's torn between pressing the matter and letting Boba get his wish. Rex may have no clue how to talk to Boba but each response has him repressing a sigh at how instead of closing the distance between them, he only widens it.]

I will not lose another brother if I can help it.

Stay out of trouble and keep away from my blasters and you won't have to deal with me unless you want to.

[Does he know there no way Boba can stay out of trouble? Oh yes.]