No one had witnessed Theia and Thunder mating. Initially, Theia was just relieved and determined to not do it again. It had been a massive lapse in judgement. Thunder was likely to leave soon anyways.
But while most of the royalists left, Yevgeney and Thunder remained at the riding school. Dmitri and Yevgeney took charge of the pregnant mares' care, having many secretive conversations about them. Theia was secretly glad to have the mares no longer be her charges. They were kept in the same private stable as Thunder, after all.
One day, Theia was in the main stable when she caught Thunder's scent again. She followed it. The stallion was in a formerly empty stall, looking forlorn. He explained that he had been moved because he mated with the lovely Arabian.
"Without you available, I had to settle," Thunder neighed. Theia could see his cock hardening.
"We can't," she hissed. "What if someone sees?"
"Does that not make it all the more sweet?" Thunder asked. Theia couldn't resist any longer. She ducked into the stall and turned into her horse form. Thunder plunged himself into her without further invitation. Theia whinnied in ecstasy.
From then on, Theia volunteered to take care of Thunder. Yevgeney was too distracted by the mares to give his stallion the appropriate exercise and attention, and gladly agreed. Theia began riding Thunder twice daily through the woods. When they got to a private glen, she would change to horse form, and Thunder took a turn riding her. Theia couldn't believe how fantastic of a lover the stallion was. No human could compare.
Months went by. The mares were fussed over and doted on. Thunder thrust his manhood deeper and deeper into Theia, filling her with larger and larger amounts of his seed. And Theia realized that her liaisons with Thunder hadn't been free of consequences.
She was pregnant.