Deke DuFresne

''"I had a little brother. His name was Deke. He died. Drowned, specifically. We were alone, by a river. I looked away for just a second, and… I pulled him out of the water, but I-I didn’t know CPR. All I could do was feel his pulse fade, and… stop." - Doc talking about Deke in 'A Pizza the Action' ''

Deke DuFresne was the little brother of Frank Dufresne (Doc) who apparently drowned in a river and when his brother tired to save him he didn't know CPR and could only watch while Deke slowly died. Deke's death sparked Doc's desire to help save lives and become a medic.

Trivia

 * Deke is the only known relative of Doc's