KENSINGTON, Conn. — The unofficial Chicago Bulls fan club of central Connecticut gathered around a 110-inch television one Thursday earlier this month. One family composed most of the club, four parents and two siblings who live here within half a mile of one another, the entire brood close by, always, except for one.

The face of the absent one filled the screen midway through the first quarter of the Bulls’ game against the Miami Heat. Career mementos sat nearby, decorations for the fan cave, autographs from Yao Ming and Patrick Ewing and Derrick Rose, a framed Ray Allen jersey, a signed box score from N.B.A. Commissioner David Stern.

The assembled knew him as Tommy, son of Tom Sr. and Ann, brother to Janet, Dennis, Nancy and David. The N.B.A. knows him as Tom Thibodeau, 54, the reigning coach of the year, the fastest ever to 100 regular-season victories and perhaps the most obsessive person in a profession populated by those proud to be obsessed. He took his last vacation to, well, no one can recall when he took his last vacation. Confidants describe him in terms usually reserved for addicts.

His family says Thibodeau (pronounced THIB-uh-doe) — who inspired his mother and her friends, a group of women in their 70s and 80s, to invest in the N.B.A. League Pass television package and swear at officials working Bulls games — is not the drone they watch at news conferences, not a recluse who spends his days in a basement studying game tape in his pajamas.