Upon fleeing from the scene Remus has just encountered, he runs into the last person on earth he wants to see, the only person who could most vividly remind him of Sirius. Regulus is lurking in a corner of the bathroom on the fifth floor, where Remus has come in the hope of solitude in which to fight back the tears that are treacherously threatening to overspill. A slightly less stunning version of Sirius, sitting right here, holding a bottle that catches Remus's eye with a green glint. "My brother do something again?" That smirk; how does he know?
Remus doesn't want to tell him that he only saw his mate snogging a girl, (Merlin knows he's seen it before, many times), doesn't want to tell this doppelganger that this time was just one too many, that he's ashamed of his envy. Green with envy, he thinks ironically, eyes falling on the bottle once more.
Regulus notices and grins. "Care to partake?"
Remus stares at the almost glowing green until it's beautiful and inviting and peaceful, and so...Slytherin. His mouth turns up at one corner and he takes the proffered drink with a shrug and a quick swipe at his eyes.
"Why not?"