Nicky and Joe are alphas and Booker is an omega. For some reason he is unable to surpress his heat (they're kidnapped by an enemy locked in a room somewhere, Booker has been in a bad mental state and not taking his suppression meds, insert other reason). Booker can feel his heat coming on but doesn't say anything bc he's bad at communicating and doesn't want to be a burden, even though he's secretly dying to be their omega. Joe and Nicky realize he's in heat and take care of him with lots of praising and telling him how much they want him. Booker initially feels guilty for "making" them do this but they prove to him how much he is genuinely wanted.