I can't believe I'm searching for a RPF but I lost the bookmark for it...

I'm pretty sure it was a Gen story, the baddies were two guys who had problems with the police in the US, so they went to Canada. They get temporary work on the crew of SPN and decide that Jensen will be their next victim after they see the Js joking around.
They manipulate the set, I remember something about a changed mark for a fight scene?

Thanks for the help