I love the idea of Regulus having two boyfriends (James and Barty), but they’re not a throuple. They’re just dating Regulus at the same time and competing for his attention 24/7
Barty and Regulus first met at a school play when they were kids and Barty was playing a lion. Years later when Reg transitions he picks the name Regulus because it’s the heart of the lion
past bartylus where they broke up only a few months ago, barty is seeing evan and regulus is seeing james, when regulus discovers that he's pregnant, but he discovered it a bit late into it so the baby is actually barty's
Super picky eater Regulus vs James who makes him try his food (Reg flat out refuses at first but after the first bite he makes James switch plates with him)