Yes, she deserves it

She stands up as if she was still waiting for something... You look at her, she is also wet, just as much as you were and still are... You feel you must give something in return for the services you have just received... You grab her big breasts and pull her over you. You start sucking one of her nipples and griping the other, while rubbing her pussy with your free hand... She can barely hold herself on all fours as you are stimulating all her sports... She keeps moaning as you keep up your work and as a result, soon she squirts over your body... She is horrified of making you dirty and quickly runs for a towel to get you cleaned.

Slave woman: I am sorry lady, I'll clean you up right away! Forgive me for the mess I have caused!

Lily: Don't worry about it, that shows we have both enjoyed ourselves! You deserved it, you gave me great pleasures, it is only fair I return the favour. Don't worry about the mess we have caused, I'll clean myself up, you could do the same. You may go now.

Now that you have brought her some pleasure in exchange for yours, you can depart. You meet Johanna outside, she gives you a strange look, but doesn't ask about what has happened inside. She can imagine, but she has never had sex with a woman before... She had sex with Peter many times but not a woman... Still, seeing her lady do it so casually with a slave has left a certain distaste for her... But her opinion is not of your concern.