Jegulus song fic: Cornerstone by Arctic Monkeys
James using Reg because he looks like Sirius
Regulus knowing that he probably shouldn’t let James call him Sirius but he really doesn’t care
At the end of the day Reg gets James even if it’s just sex, James gets the closest thing to Sirius, and Sirius doesn’t know a thing lest he become traumatized by what his brother and his ex get up to.