Reaper being overly competitive (particularly with Soldier) for absolutely no apparent reason.
Soldier 76 building a card tower. Reaper comes in and constructs a giant one and kicks Jack’s over.
Soldier 76 gets a cat out of a tree. Reaper spends a week finding as many cats as he can and putting them in trees just to video tape himself getting them all out.
Reaper flips 76 off every time he gets a head shot.
Soldier 76 is just extremely tolerant with the occasional sigh.