So he hears Irahl hit something before opening the door to find the sniper looking discombobulated and Vincent next to him, under his coat, with a pillow underneath his head and a familiar look of half-awake confusion on his face.

To be fair, Robin is also confused by what he's seeing, though this confusion manifests more by him standing in the open doorway and looking thoroughly unimpressed. Either Vincent pulled some stunt to steal that coat and trick Irahl to agree to hold still long enough to fall asleep on him, or... Irahl did it willingly, neither of which Robin can fully process as logical possibilities.

"Cozy," he comments, wanting to fill this weird space with something other than Vincent's grumbling, "Time's up, ladies."

Vincent at least manages to sit up and pull off his very heavy, weapon-filled coat.