Basic Trope: Someone takes a lesser revenge on someone else in liue of forgiving them entirely.
Straight: Alice plans to kill Bob for killing her brother in a duel. After getting to know Bob (and realizing that it was just a terrible accident), she opts to avenge her brother by turning Bob in instead.
Exaggerated: Bob murdered Alice's entire family For the Evulz. Alice decides to let him go with nothing but a punch in the stomach.
Downplayed: Alice decides to give Bob a chance to survive by merely leaving him stranded in the middle of the desert where she confronted him.
Justified: Bob killed Alice's brother in self defense. While Alice is bitter, she knows he was in the right and once she gets to know him as a person, rather than just the faceless killer of her brother, she can't bring herself to kill him.
Inverted: Alice planned to simply turn Bob in once she'd found her brother's killer...however on meeting him, he turns out to be a monster and she decides to kill him instead.
Alice was just grateful for Bob doing something earlier; she will still kill him later, just not now.
Double Subverted: Of course, this was actually a sign of hesitation. She's forgiven him, even though she won't admit it.
Parodied: Alice reveals that she'd sworn to track Bob down and do the worst thing she could imagine...when she was a child. Bob has to live with the fact that he's just been called "The biggest meanie ever!" to his face. It pushes him into the Despair Event Horizon.
Zig Zagged: The show can't seem to make up its mind whether it's better to drop grudges and whether or not taking a token revenge is reasonable.
Averted: Alice just kills Bob as planned and considers everything even.
Reconstructed: Bob's family realize that killing Alice was Disproportionate Retribution and agree to allow a third party to take him into custody rather than wait for Alice's family's vengence (and carrying out their counter-vengeance, etc). By avoiding escalating the grudge, Alice signaled the beginning of the end of the cycle.
Played For Laughs: Alice's revenge leaves Bob humiliated and is suitably ironic.
Played For Drama: Alice met and fell in love with Bob before finding out what he did and who he actually was and saw a spark of goodness in him. After sparing him, she's torn over whether or not Bob truly is capable of being redeemed or if she's simply allowed more innocents to die by Bob's hand.