Author's Note

"I dare you to write Big Mac getting gender swapped with his sister, and he immediately goes into heat. He reluctantly goes along with it when AJ mounts him and screws him, impregnanting him." - Marshal Twilight

Big Mac x Applejack (Bad_Seed_72)

When Big Mac woke that morning, he felt oddly itchy between his hindlegs. After yawning and stretching, he rose from the bed and walked from his room to the living room. Everypony was still asleep, and he was still itchy. Trotting over to the freezer, he decided to go ahead and sneak himself a little relief.

After grabbing an ice pack from the freezer, Mac placed it between his hindlegs. “Errr… Ma balls are a-twitchin’... Wait a darn second…”

Big Mac felt something else back there. Something that was most certainly not his dick and balls.

Big Mac headed into the bathroom as quickly as he could, that itchiness getting worse by the second. Once inside, he turned around in front of the mirror, then gasped.

“Ah’m…AH’M A MARE!”

“Big Mac?!”

Gasping, Big Mac turned to see Applejack approaching him. Well, it would have been Applejack, if it were not for the erect stallionhood smacking against her belly and the two heavy orbs swinging behind it, along with the boxy snout and larger body.

Big Mac pointed at the swapped genitalia. “Those… Those are ma…”

“Eeyup, an’ you have ma cooter,” Applejack said with a snort. “Looks like we’ve been switched, brother. Lemme take a look at it.”

“Uh… Okay…” Mac mumbled, turning around to present herself to Applejack.

Applejack took a deep whiff of her marehood, then grinned. “Feelin’ funny, Mac?”

“E-eeyup… Itchy… An’... Warm,” Mac said, feeling herself starting to heat up back there.

“Ah know what’ll fix that…”

Suddenly, Applejack was on top of her, his thick head teasing at her entrance.

Mac gasped and tried to buck the stallion off her, but he was too strong. “A-AJ! What in tarnation are ya doin’?!”

“Helpin’ out ma sister, o’ course,” AJ said shyly. “Besides, ya know ya want it… It’ll only get worse from here on out if ya don’t let me buck ya…”

“It gets WORSE?!”

“Eeyup. So… what’s it gonna be? Ya wanna roll around like a mare in heat an’ have some strange stallion buck ya, o’ have somepony ya love take the edge off?”

Mac paused. While she never had thought about her sister—er, brother—like that, Applejack was making good sense. The burning, itching sensation was quickly becoming unbearable. Mac’s body screamed at her to be penetrated, and be penetrated now!

“Haah… All… Alright,” Mac said with a slight grunt, lifting her tail high. “Go… go ahead.”

AJ licked his lips. “Good mare. Now, jus’ hold on tight…”

And then they fucked.

Applejack came inside Big Mac. Eleven months later, they had a lovely little incest foal.

The end.