1. Eat it.
2. Feed it. Taste the suspicious potion, food, lake water, and the oozing liquid on the floor. Or, just put the sample on things the rat might like.
3. Feed it to. Anything really, and see what happens.
4. Free it. Let the rats run amok!
5. Kiss it. Just incase its a cursed prince.
6. Lit it. Burning rat on a stick, or tie a cloth soaked in oil on its tail and let it loose. It'll take down any wooden building.
7. Make a rat king. Tie their tails together.
8. Gift it. You'd be surprised at how many witches' cats, wizards' owls, monsters or goblins are okay (delighted even) with a rat on a stick. Might be impressed by your rat king.
9. Bait it. Fish out the cats, owls, whatnot.
10. Love it. Instead of all the cruel things above (and far below), I guess.
11. Befriend it. They might just be the ticket to leading you out of a tunnel.
12. Whisper to it. Rats know a lot of things. Cheddar might be on the forefront of their minds, but if you lived in a castle long enough, you are bound to overhear something.
13. Pet it. Kids love rats, you don't know that? If they don't, put a bow tie on it, call it a princess and try again.
14. Play tricks with it. Yo-yo the rat, juggle it, make it walk on tights, play with the cat.
15. Animal companion. Same as above, but you train it to do stuff. Depends on your GM if they allow this outside of a Hunter class.
16. Crack a cold one. Snap its neck off, and you've got a cuppa'rat.
17. Stay warm with it. Again, drinking animal blood, or just keep it as a heat pocket.
18. Skin it. A few rats are enough for a new sole, a glove, or a towel to clean up a mess or to avoid touching the cursed shit.
19. Fake moustache.
20. Draw with it. You got everything you need when you lost your quill or charcoal. Blood as ink, tail as pen, pelt as parchment.
21. Stamp with it. Same as above, but you squash the rat. Simple, effective way to mark a foe. If you have a hound, you can easily find the stench.
22. Let the rat touch the magical cursed shit. Beware if it supercharges the rat.
23. Drop it down a hole or a cliff. If there are no rocks around. But if you tie it to the end of a string, it may pick something up. Otherwise, dip it in glue.
24. Put it on a pole and let it go first. Through a gateway, through gas, through magic trap tiles that react to organisms only…
25. Let it carry things. Through narrow cracks, threading a rope through a tunnel, or a flask of oil to trace a line of fire!
26. Use it for torture. Gnawing off toes, putting them in pants and watch your captive dance.
27. Diseased Nunchuck. Is a rusty sword not enough for you? Try swiping at them with a dirty rat!
28. Dip it in oil and hold onto its tail. You have a hanging torch. The fatter the rat, the better.
29. Teach it to come to you on command. Rudimentary conditioning & pathfinding tool.
30. Vermin in a coal mine is a safe, poison-free coal mine!

Rats are my go-to multitool for a variety of situations. What you will find is that a rat simply acts as a substitute for the player when interacting with a lot of things—a laboratory mouse. Most importantly, rats are easy to carry once you have a small chest, a wide-opening bottle or a cage. The hard part is catching them…