First he cums, then has them decide who gets to fuck him.

Natsu moaned and bucked his hips as both girls kept on fucking him with their tits. "Good girls, I'm gonna cum soon!" he groaned out, and both "Lucys" kept going, determined to taste his seed. Even with him more focused on the contest, his body was still responding appropriately to the sex.

With a pleasured groan, he released his seed, coating both of their faces and their tits. Both girls panted and moaned, licking it off of themselves. "Now what?" Erza asked, looking adoringly at Natsu.

"Yeah, what's next Master?" Lucy asked.

"Well, why don't you two try and convince me which of you should be fucked first?" Natsu grinned at them.

"Oh, of course, and I have just the idea!" Erza replied, reaching for her shorts... And realizing something was missing. "Wait, where are my keys?"

"Right here, and they're mine!" Lucy replied with a cat that ate the canary look as she held a golden key up.

"Hey, you stole my keys!" Erza huffed.

"No I didn't!" Lucy stuck her tongue out, even as she Summoned Virgo.