You were impatiently waiting for the farm hand to leave the barn already staying silent and still so you wouldn't draw attention to yourself. Zeus was simply watching you amused no one dealt with him but your uncle and when you had come in well... that was how you ended up in this situation. You could tell you were already in heat and felt your body changing as you lay there waiting impatiently your hearing becoming sharper as your ears changed and migrated your hair growing out a bit as well along with your tail impatiently swishing behind you.
After what seemed like hours but in reality couldn't have been more than 15-20 minutes at max you FINALLY heard the footsteps retreat and the barn door open and close as the hired hand left. Once he was gone you impatiently got up a bit unsteady and kissed Zeus hungrily before lowering yourself to all fours as you lifted your tail "Fuck me. Give me your foal Zeus!"
Zeus laughed as he became hard again sliding into you with no problem as you were already wet. You could feel your walls clench around his member as they tried to milk it while he slowly began to go in and out of you at a steady pace once more. It was torture but of the pleasurable kind. Pushing yourself back against him you snorted a bit impatiently making him shake his head amused and start going faster until he slammed into you and stilled as he came his cum apilling into you again further enlarging your stomach which had begun to go down as your body used it to fuel the changes so you would be perfect for him. As he came in you you came at the same time your walls milking his hard hot shift for all it was worth whinnying in pleasure at your release.
A few days had passed and you noticed your scent change grinning once you did Zeus smirking "Looks like my mare is finally pregnant with her first foal."
You nodded eagerly "Yes! I can't wait." You knew you wouldn't be able to do much once you got larger for now your changes were hidden easily enough but the large stomach you would soon sport throughout the pregnancy wouldn't be hidden as easily. You didn't overly care much anymore and were comfortable with staying in the stall with Zeus eating what you were fed and being fucked constantly.
Your heat was finally over now that you were pregnant but it didn't stop you from wanting sex. As per normal you got down on all fours lifting your tail to reveal your pussy already wet the slick running down your legs glistening in the sunlight that streamed in through the windows your lips winking as they opened and closed looking for your mate's cock eager for him to enter you.
Zeus was already hard again as he approached his mate his shaft dripping with pre and throbbing as he lined himself up before slamming into the smaller body beneath him the mare whinnying in pleasure as he finally entered her