From what Sirius could tell, Regulus had created a weird uncle-like space for himself in the family. Lily had a demanding job as an endocrinologist and James was an up-and-coming sports commentator, so Regulus—who was smart enough to wait for his trust fund to become available before escaping their family and so would never need to actually work—stayed at the Potter manor, worked on an indie gaming project, and took care of Harry when the kid wasn’t at school.