James:
Quidditch. Whether you're playing or practicing together, even just cheering in the stands, you both find so much joy in the sport together.
Sirius:
Dancing. When Sirius found out you were a dancer, he would take every chance he got to spin you around or hold you close.
Remus:
Reading. The two of you loved how quiet it was and would sit with each other for hours at a time, enveloped in the books you were reading and each other.