Reciprocity

[Britney]

Reciprocal advantages, obligations, or rights;
reciprocation.

[Marquetta]

The [expectation], knowledge or at least hope, that somewhere [down the road] you will be repaid for an action you were responsible for. In negative terms, its [revenge].

[Renato]

The practice of exchanging things with others for mutual benefit, especially privileges granted by one country or organization to another.

[Justin Bieber]

behaviour in which two people or groups of people give each other help and advantages