I'm looking for a specific M/A fic involving non-con. I actually remember the specifics really well, but I can't find it. Basically Merlin gets caught at the end of a spell that was meant to bring the end of a drought. While the person who catches him has no proof it still looks pretty suspicious and it is taken to the king. In order to know for sure if Merlin is a sorcerer Uther makes Arthur rape Merlin under the logic that if Merlin was a sorcerer he would use magic to escape.
I can't remember why, but I know that Merlin doesn't use magic and instead tries to fight back the normal way. I can't remember what happens afterwards, but I'm 90% sure that it leaves an opening for a manipulated!Arthur and a slightly insane!Merlin who doesn't hate Arthur, but instead Uther. I think it might have been posted over at the kinkme_merlin and the title had the word crops in it, I think.