Merriam Webster On line definition:
Quid pro quo
noun \ˌkwid-ˌprō-ˈkwō\: something that is given to you or done for you in return for something you have given to or done for someone else
Harper Ellis is a Broadway Star who lives a carefree life. She’ll be who she is and not be committed to any one person.
Blair Alexander is the now retired Olympic champion swimmer. He’ll be who he is and not be committed to any one person either.
An evening at a club and an erotic encounter, sees Harper and Blair agreeing to Quid Pro Quo.
What she gives, he must match or better.
What he gives, she must return.
Is it just an arrangement, or can it develop into more?