Tumblr Merlin fic
Need help finding a fic I read on tumblr a while back. Group of bandits or mercs (or whatever) have a collar that can control someone it they have the other piece to it (i think it was a key but idk). They capture Merlin while he’s in a field (I think) and put it on him.
Arthur and the knights track him down to a barn where they have him doing things like hurting himself. They try to sneak in but are caught and the leader makes Merlin attack them. Arthur gets the object and makes Merlin attack the bandits and they escape. He then has Merlin remove the colla.