They could surely check but they'd never get in without the same intentions in their hearts. That wouldn't stop Sirius from grilling him. Especially when he saw that Remus and Snape were in the same place. Unmoving.

Severus frowned and looked passed Remus's shoulder. "A loo?" he asked, curious himself if they'd discovered a warp-around-Hogwarts bathroom filled with toilet paper.

Wouldn't that be something?

He did not find a room filled with paper at all but one with a bed and a desk and a small coffee and tea service. Severus arched an eyebrow.

"Looks like a professor's chambers."