You are Terezi Pyrope and, like your friends, you are coming to your sense in a tasteless prison cell. Upon discovering the note you sniff it cautiously, then lick it thoroughly. Having digested its contents (somewhat literally) you stick the soggy remnants in your pocket, then take the only sensible course of action.

You take the key from where it is lying on the floor and try it in the lock. The difficulty comes when you realise the key does not, in fact, fit. You jiggle it around to be sure, but it's futile. The key was not made for this lock.

This is a setback.

You try sniffing the key. There's nothing special about it; you smell only the tang of metal. You sit on the floor for a few moments, contemplating the situation, then press your nose to the lock. The scents are muffled by the same metallic tang, but beyond that you make out a few small things. The corridor outside is just the same as your room, disturbingly sterile. Someone is walking down the corridor, though they're moving slowly. you can make out very few details, though it's clearly a troll.

You weigh up the pros and cons of calling out to them, though in reality there's very little choice. If you don't you have no idea how long you'll be stuck in here.

Terezi: Get their attention.