In “Out of the Furnace,” which opens Friday, Russell Blaze (Christian Bale, right) has to rescue his brother Rodney (Casey Affleck). Because movie brothers bail one another out. Or hate one another. One of the two.

Thor and Loki
Loki never quite sees eye to eye with his Thunder God brother, who got a 2011 film (and a 2013 sequel) named after him. Possibly because he would need stilts to get to Thor’s eye level.

Brennan and Dale
Sometimes idiocy is thicker than blood, like in 2008’s “Step Brothers,” where Will Ferrell and John C. Reilly play middle-aged losers who have to start sharing their toys when their parents get married.

The Ryans
In Steven Spielberg’s 1998 masterpiece “Saving Private Ryan,” the Army sends out a group of soldiers to safely bring back the last remaining of four Ryan brothers who hasn’t been killed in action. In doing so, at least four other mothers lose sons. The logic of war is often illogical.

Norman and Paul Maclean
It’s good for brothers to share a hobby. In 1992’s “A River Runs Through It,” these brothers (Craig Sheffer and Brad Pitt) both love fly fishing and suppressing their emotions.

Sonny, Michael and Fredo Corleone
In 1972’s “The Godfather,” Sonny (James Caan) is the Corleone who gets himself killed, largely thanks to his ego; in the 1974 sequel it’s Fredo (John Cazale) who gets whacked, for crossing Michael (Al Pacino). And possibly for stealing Michael’s toys as a kid.