Grandpa Chapman is the grandfather of a serial killers, Billy Chapman and Ricky Chapman in Silent Night, Deadly Night
His minor story[]
It started on Christmas Eve, 1971: Billy Chapman, his parents and his infant brother, Ricky, are on their way to visit Billy's institutionalized grandfather.
At the institution, Billy's parents review the catatonic grandfather's records with the doctor, leaving Billy and the old man alone.
With the adults gone, Grandpa suddenly becomes lucid and giddily tells Billy the terrible, secret truth about Santa Claus: he not only gives presents to good boys and girls, he punishes naughty ones.