Not, Riku wasn't born a servant. If not for being stolen from his family, his home, he would not be one now either. If he'd been allowed to work for a few more weeks, then he could have bought his freedom now. But the Prince had insisted, so Riku was still legally a servant.
Riku smiled at the Prince and shook his head. "I should have guessed!" he exclaimed. Not EVERY horse keeper could be terrible; they couldn't all not know what they were doing so that Riku, not magically talented with horses, should somehow do THAT much better than everyone else.
"Either way," he added, "I am glad that you gave everyone before me such a hard time. It left a place for me to enter, and meet you." If it hadn't been for his job with Orion, would have have ever met the Prince? The castle was large, and there were many servants. Yes, there was a good chance they might have never become close if Riku didn't work with Orion.
"You, my Dear," Riku said. Difficult? Yes, a little. But rewardingly so. "Are a rare delight." Not everyone could get to the sweet center that was the Prince. But those that could were truly blessed with so kind and caring a person.