Everyone knows the tale of former Patriots defensive coordinator Eric Mangini. Mangini started his career in Cleveland as a ball boy for then-Browns head coach Bill Belichick, before following his mentor to the Jets and Patriots. Mangini became defensive coordinator in 2005 and took the Jets head coaching job in 2006.

Belichick told Mangini to not take the Jets job, but to wait for a better opportunity (and you can be certain the same rules applied to Josh McDaniels, Matt Patricia, and Nick Caserio with the Dolphins jobs). Mangini broke Belichick's trust by taking the head coaching role and then trying to recruit Patriots staffers to join him in New York.

Then Mangini called in the league over SpyGate, and the rest is history. Except for Belichick. He'll never forget.

Mangini was fired by the Jets, and then fired by the Browns, before joining the San Francisco 49ers in an advisory role. He served as the tight ends coach for two seasons before taking over as defensive coordinator in 2015. The 49ers were an absolute disaster and the coaching staff was canned.

Former Eagles head coach, and Belichick's bud, Chip Kelly took over for the head coaching role in San Francisco. Former Patriots linebacker Mike Vrabel interviewed and was offered the defensive coordinator role, which was still technically held by Mangini. Who was Vrabel's biggest supporter?

None other than Mr. Bill Belichick himself.

"Mike Vrabel turned down an offer to become 49ers defensive coordinator on Thursday," NFL Network's Albert Breer wrote. "But just getting the invitation after his fifth year as a coach (second in the NFL) is pretty remarkable...the decision for Vrabel (who was strongly recommended to Kelly by his former coach, Bill Belichick) was a tough one, and as much about family and loyalty to Bill O'Brien as anything."

Vrabel was offered the job on Thursday, declined it, and Mangini was still fired on Friday. The former Patriots linebacker showed the loyalty to O'Brien that Belichick wished Mangini had showed back in 2006, and Belichick will always offer his support to those that don't break his trust.

As for Mangini, you can be certain that Belichick will continue to haunt him wherever his next stop may be.