Remus Lupin was a very tidy man. Sirius Black was about as tidy as a four-year-old boy with ADHD.
As Remus eyed the mess Sirius had made in their bathroom that morning, he decided that it must be love. And as he cleaned it up, he heard the sound of jazz playing in the living roo.
Yes. Love and old jazz records. A smile crossed Remus' face, and he finished cleaning, to go join Sirius.