Well, there is a certain style for doggies...

Natsu watched as she ate her meal like a dog, chuckling at the sight. "Wow... That just seems awesome..." he grinned.

She finished and looked up, panting at him with her tongue lolling out and shaking her ass. "Woof!" she yipped out.

"You in heat girl?" he teased her.

"Aroo..." she agreed. He knelt behind her, releasing his cock as he did. Pulling her panties aside, he lined his cock up and pushed into her. "Arf!" she cried out.

"Good girl Erza," he moaned as he began to slowly fuck her as a dog. She clenched her hands, or her "paws," and leaned forward so her face was on the floor, her ass still raised.

She whined in pleasure while he grinned and sped up a bit. She looked back at him with literal Puppy Eyes, begging him to go harder still with a whimper. Deciding to oblige, he began to pound into her, and she yelped out happily.

He leaned over her a bit as he kept wantonly fucking her in a literal Doggy Style, petting her head with one hand, and groping one of her boobs with another. She blushed deeply and panted again, but more frantically than before.

Before long, her tight pussy succeeded in making his cock pulse, and she yowled as she came, him grunting as his seed gushed into her depths. Wheezing, she collapsed, and rolled into her back, panting and giving him a derpy smile.

"Ah, who's a good girl?" he teased, rubbing her belly, and making her wiggle in ecstasy.