One former rival head coach just did the ultimate plot twist for the Kansas City Chiefs

Before this last Christmas Day game, the last time the Las Vegas Raiders beat the Kansas City Chiefs, the then-Jon Gruden Raiders decided it would be funny to do a victory lap around Arrowhead Stadium.

Obviously, that didn't work out well for the Raiders, as the next time they would show up in Kansas City, they were beaten down 48-9. In a way, it was Patrick Mahomes and Andy Reid's way of sticking it to their biggest rival of all time. But, the rivalry didn't end there, and why would it?

Then the Raiders beat the Chiefs in Arrowhead on Christmas Day, and of course, the Chiefs heard about it for the next few months, that is, until they won the Super Bowl in the Raiders stadium -- before the Raiders won a playoff game there. So, there is still plenty for the team to go back and forth on.

But one thing I absolutely would have never placed on my bingo card is Gruden helping the Chiefs, Yes, you read that right -- a coach who is universally thought of as a Raiders, whether it be in the late 90s, early 2000s, or just a few years ago, he is a Raider.

Well, let me rephrase that -- he was a Raider. Now, he is helping the Chiefs at training camp. It's one thing to help them and wear your regular clothes. Sure, the Raiders fan base may wince a bit but they understand that football work isn't coming often for Gruden right now, so, it's somewhat about getting a job to help wherever he can.

But putting Chiefs gear on is one that that will make Raiders fans absolutely sick. It feels as if we are living in upside down, with how Gruden just did one of the biggest plot twists you will see from a coach.

From a Chiefs perspective, Gruden is one of the smartest football minds ever, so, that could be helpful.

Related: Chiefs' Patrick Mahomes still has the Christmas Day loss to the Las Vegas Raiders on his mind