Makes Us Even

Alice does something for Bob (most often this is saving their life)... then later Bob returns the favour, and one or the other will say "That makes us even" or "I guess we're even".

A malicious variant is when Alice wrongs Eva (or at least Eva thinks they did), and when Eva gets her revenge, she will say "NOW we're even"

See the other side of this, You Owe Me.

Anime

 * In Sonic the Hedgehog: The Movie, Sonic and Knuckles save each others' lives during the fight with Metal Robotnik, and Knuckles declares that they're both even. Later, during the fight with Metal Sonic, Sonic steps on Knuckles' head (at Super Speed!); after the fight is over, Knuckle punches Sonic in the head and declares that they're even again.

Film
"Trinity: I guess this makes us even."
 * The Matrix Reloaded. At the end of The Matrix, Trinity saved Neo's life by giving him a How Dare You Die On Me speech. In Reloaded, after she's mortally wounded he returns the favor. Afterwards:

"Jack Wilson: [after Jack rescues Philo in a brawl] I believe that makes us even."
 * Any Which Way You Can

"Murtagh: [Shouts as Eragon flies away] I guess we're even!"
 * Eragon: Murtagh saves Eragons life part way through the film. In the final battle Eragon takes care of the enemies who have Murtagh surrounded:

Live Action TV
"Jack: Well, MacGyver, you saved my hide again. I guess that makes us even."
 * MacGyver

"Max: Liz. You brought me back.
 * Roswell episode "Max in the City"

Liz: I guess that makes us even."

"Dean: So hocking over ten grand is easier for you than saying "thanks"? Wow, you're damaged."
 * Mr. Chapel's Catch Phrase in Vengeance Unlimited is "We're even, and I'm out of your life forever." Invariably, the response to that is, "Thank God."
 * Supernatural: In the episode "Red Sky At Morning", Sam and Dean, while fighting the Monster of the Week, end up saving the life of recurring rival Bela; at the end of the episode, she gives them $10,000 in cash, saying that makes them even.

Tabletop Games
"Liriel: So, what's the score now?
 * At least in Forgotten Realms, Drow has an interesting variation: they usually just don't get a concept of altruism, but Chronic Backstabbing Disorder is counterproductive more often than not, so what to do? Keep scores. Drow being more inclined to act for sport than out of obligations, it's not a score of debt, but a score in the "game".

Fyodor: The score?

Liriel: The score. You know: I've pulled your tzarreth out of the fire four times, you've saved mine three--that sort of thing. It says something, doesn't it?"


 * Magic the Gathering: In Agents of Artifice, Jace saves Baltrice's life on Kamigawa, and she returns the favor when.

Videogames

 * In Halo 3, Sgt Johnson says "We're even... as long as we're only counting today," after being rescued by the Master Chief, Johnson having found and revived Master Chief earlier.
 * In Star Fox 64 if you save Falco in the asteroid stage, he will appear a bit later and kill a couple of enemies, telling Fox "that makes us even". It is unknown how killing a few enemies that would heavily damage Falco is even to killing a few foes that would have great difficulty heavily damaging you.
 * A one-sided variant in Uncharted 2 Among Thieves from Nathan Drake toward Tenzin since they speak different languages. Nate catches Tenzin's hand and pulls him up to the ledge declaring "You owe me one, pal", of course, with Nate's luck this lasts about fifteen seconds before Tenzin has to save him from ground breaking beneath his feet.

Western Animation
"Demona: Thank you.
 * When Demona battles the original Hunter in Gargoyles, she allows him to escape to save MacBeth. Years later, in the battle when MacBeth kills the original Hunter, he saves Demona, prompting the following exchange.

MacBeth: I owed you.

Demona: Good. That means we're even."


 * Used and parodied in "Phineas And Ferb". Baljeet one day saved Buford's life, and thanks to "The Bully Code" becomes his slave for the rest of his life. Baljeet quickly becomes creeped out and annoyed by this "60's sit-com cliche", and spends the episode trying to settle the score. Eventually he's convinced that having someone follow his every whim isn't such a bad thing...at which point Buford saves his life, making them even.
 * In Transformers Prime, Starscream name-checks this trope when he has Arcee at his mercy and spares her, pointing out that she had done the same in their last fight.