Samantha is giving you a wonderful blow job. Not that there really is another kind. But you are enjoying your shower a lot more as she works away. And since vore girls have those really flexible mouths and throats, she is able to do things mere humans can't. As the water splashes down on you two, you are thinking this is going to be a really memorable time.

But all good things come to an end. You feel yourself building and then feel your hot seed spill into her, to be quickly swallowed. As you lean back against the wall in satisfaction, she looks up and asks "Well, have I thanked you properly?" Her smile suggests she didn't find the thanking very hard work.

"Yes, that will make an excellent down payment." is your answer.

"Down payment? What do you mea..?" is her puzzled response, until she realizes you have grabbed her and are positioning her to fit into your maw. "Hey! Wait! I didn't say you could eat me."

"You ate me, so I eat you. Seems fair to me." is your counter as you continue in your design.

"Well, it is not fair." is her biased response. "You just stop it, or..."

There really isn't much of an or. She is meat, quite tasty meat, if you want it. Just chow down if you feel like it.
Still, it might be better to persuade her to be a snack. As much fun as the oral sex is, she still does owe you and maybe you can get her to pay up. And you can probably use her in a good mood towards you.