Fairly well, considering the flood.

The stall door swung open with a creak.
Hermione already knew something was wrong before she saw it. The water in here was deeper than the rest of the bathroom, and the smell was different — fouler, something underneath the cold damp that made her stomach turn. She looked at the toilet.

It was overflowing. Not just sitting full and unusable — actively overflowing, water and worse rising up and over the rim in a slow continuous pour, the source of the entire flood spreading outward across the tile.
The plumbing was completely blocked. Unknown to Hermione, a group of third-years had thought it was a fine idea to stuff the pipes with expanding Spongify-ed material as a prank two hours earlier. But then, cause hardly mattered.
The result was the same.

From somewhere deep in the pipes, something wailed.
Hermione stood in the stall doorway and looked at the toilet.

Of course.
She'd passed through both of those somewhere in the second floor corridor and come out the other side into a kind of bleak clarity. She was naked, filthy, had already leaked once, and was standing in overflow water in the worst bathroom in Hogwarts while Moaning Myrtle mourned somewhere in the pipes.
This was simply what her evening had become. The universe had made it clear, and she had approximately thirty seconds to respond.

She looked at the toilet. At the stall walls rising on side. At the door she could pull shut behind her.
It's still a toilet, she thought. It still counts. It took her approximately two seconds to reach the conclusion. She had always been efficient under pressure.

Hermione pulled the stall door shut behind her and sat down.

The relief was immediate in a way that only the end of something truly desperate can be — not pleasant exactly, more like removal of something that has been consuming her entirely. She didn't realize quite how much of her focus had been devoted to holding on until she let it go. Her shoulders dropped.
The muscles in her thighs, clenched for so long they'd stopped registering the effort, finally released. She sat in the awful water on the awful seat in the awful bathroom and let out a breath that seemed to come from somewhere very deep, and for a long moment she didn't think about anything at all.

After a while, she looked down at herself.
Feet submerged in the water. Skin pale in the dim light, covered with grime from hours of walking barefoot over Hogwarts stone floors, now rinsed to a different kind of dirty by the flood water.
The layers had changed — dust and pumpkin juice replaced by whatever the bathroom floor had been before the pipes gave out — but the fundamental situation remained. She was naked, filthy, and a very long way from a shower.
One thing at a time, Hermione thought. Always one thing at a time.

There was nothing to clean up with. The paper towels were soaked, and she still had to get back to Gryffindor Tower regardless, which meant getting dirty again. She would shower when she got back. Properly, with hot water, for as long as she wanted.

She stood up carefully, legs unsteady in the way that comes after sustained effort finally released.

Right. Second floor. Gryffindor Tower on the seventh. Five floors up via servant staircases and side corridors — more hiding, more obstacles, more of the same exhausting navigation she'd been doing for the past however long it had been.

The thought sat heavily.
And then she remembered.
The tapestry shortcut. On the second floor, behind a tapestry — a narrow staircase leading up near Gryffindor Tower, with a trick step she'd need to avoid. She'd dismissed it at the beginning of the night on account of too many unknowns. But she was already on the second floor, already as dirty and exhausted as she was going to get, already past the worst of it. The servant staircase route meant five floors of corridors and hiding and near-misses. The shortcut, if it was still there after the reconstruction, cut straight through.

The unknowns hadn't disappeared. But the calculation had shifted.
However, she couldn't remember which tapestry. That was a problem. She'd have to search — moving through second floor corridors, checking tapestries one by one while naked and wet and hoping no one will came around a corner.
Not ideal.
Still better than five floors.
Find the tapestry, Hermione thought. Use the shortcut. Watch for the trick step.
Get home.
She pushed the stall door open and waded out.

The bathroom was as bad as it had been when she entered — worse, maybe, now that she wasn't too desperate to register it.
She moved toward the exit without looking back at the stall, at the toilet, at any of it.
That was done. It was behind her.

She stopped and pressed her ear to the door.
Voices further down the corridor, moving close. Two people at least, one of them with the particular carrying tone of someone with authority. Filch, possibly. The flood had been reported, then.

She hadn't had much time.

Hermione cracked the door, angled her head to see down the corridor. Clear in the direction she needed to go. The voices were coming from the right; she'd go left.

She slipped through, let the door shut behind her, and instinctively resumed covering herself.
The voices were closer now, footsteps distinct on the stone.
Hermione went left, quickly, and didn't look back.

(Note: This chapter was beta’d by user qwertpoint.)