She makes him beg first!

Erza kept rubbing his cock, but continued to not let him cum for the moment. "So, do you want to cum?" she asked him.

"Yes... Mistress, I really want to cum..." Natsu panted, moving his hips slightly.

"Then beg me for it," Erza smirked, stepping a little more forcefully on Natsu's cock, and making him gasp.

"Please, Mistress Erza, let me cum," Natsu replied, his nails digging into the floor.

"Heh, you'll have to do better than that. Show me that you're my bitch for the moment..." she continued.

"Please Mistress, your pink haired bitch needs to cum! I'll even give you a small wish from Lucy if you let me cum!" Natsu begged.

"See? That wasn't so hard, was it?" Erza asked, rubbing his shaft faster with her foot until it throbbed, and released his seed onto his own stomach and he gasped out in relief.

She pulled back her foot as he panted. "Thank you, Mistress..." he panted, and she smirked.

"Hey, Lisanna, wanna clean up your Master while I consider what to ask for from Lucy?" Erza asked.

"...okay, sure," Lisanna blushed, considering whether to follow Erza's command or not, but deciding she had nothing against it anyway, and leaned down to lick Natsu's stomach.

"Hmm..." Erza mused, turning to Lucy, who smirked.

"Remember, Master has final veto rights, so keep it small," she teased Erza.