Bill Belichick and Eric Mangini, both graduates of Wesleyan University, first met in 1995 with the Cleveland Browns.
Belichick was the head coach of the Browns at the time and was fired following the season. Mangini, who was promoted to a coach's assistant by Belichick during training camp, stayed with the Browns for 1996—only to return to Belichick's side with the New York Jets in 1997.
Once Belichick resigned as "HC of the NYJ" and assumed the role of Patriots head coach in 2000, Mangini again stuck with Belichick and followed him, yet again, to New England.
After serving on Belichick's personal coaching staff until 2005, Mangini was named the team's defensive coordinator.
Just one season after running the Patriots defense, Eric Mangini left for a head coaching job with, you guessed it, the New York Jets.
Urban legend holds that once Mangini left to interview for the Jets head coaching position, someone in the Patriots organization locked Mangini out of gathering his personal belongings inside Gillette Stadium.