In Frailty , Matt O'Leary portrays 12-year-old Fenton and Jeremy Sumpter portrays 10-year-old Adam .
In the summer of 1979 , when the brothers : 12-year-old Fenton ( Matt O'Leary ) and 10-year-old Adam ( Jeremy Sumpter ) were children , their father ( Bill Paxton ) told them that he 'd been visited by an angel and tasked by God with destroying demons disguised as human beings .
Frailty -LRB-2001 film-RRB-