It doesn't take a genius to spot Frisk's handiwork, once they gather the wherewithal to get up and off the sill (the thought of someone coming across them as they are at the moment works wonders).
They pick up a shard of window as they walk down the hall, and pocket it. It's sharp enough to cut into their hand as they do, leaving a red smear on the clear glass.
They won't search for Frisk. In hindsight, they can see the signs of someone who wanted to be left alone even if they didn't pick them up at the time, or maybe ignored them, and either way it's a small drop in the bucket of reasons to dislike themself.
They could probably find them, if they wanted to, but they won't. They head down the halls. Time to move rooms again. They'll leave the other to their peace. (They might even pass them, unknowingly.)
it is late, but I think this is wrapped
They pick up a shard of window as they walk down the hall, and pocket it. It's sharp enough to cut into their hand as they do, leaving a red smear on the clear glass.
They won't search for Frisk. In hindsight, they can see the signs of someone who wanted to be left alone even if they didn't pick them up at the time, or maybe ignored them, and either way it's a small drop in the bucket of reasons to dislike themself.
They could probably find them, if they wanted to, but they won't. They head down the halls. Time to move rooms again. They'll leave the other to their peace. (They might even pass them, unknowingly.)