After the premiere episode of Reaper, I hoped Sam would progress somehow, not be doomed to fight the freak-of-the-week because his future was written. Last night's episode, like most of the series, delivered.
Andi's ex-boyfriend Greg sells his soul for mind control over Andi, and The Devil transforms Greg's pent-up rage into a chainsaw killer. At first, Sam is tempted to kill Greg, simply remove the threat. Then he learns the Devil has no power over true love. After Andi assures Sam she loves him he's able to look past his animosity. He uses his Get-Out-of-Hell-Free card to get Greg off the hook.
All of this is played very naturally, with a minimum of moralizing. Sam is turning out to be quite a foil for Old Scratch.