The Princess made a concerned face and Namine decided to try and calm him down by moving his hair around and fixing his flower circlet and maybe holding his hand.
Kairi wanted to explain, she just didn't really know how. "When he turned sixteen, he had already been fading away from us," she tried. "When his birthday came, we were not sure what to do for him. He hid all the day, even away from his own celebration. We tried, after that, but he would feel anxious over the attention. I think it made him uncomfortable to be thought about. No one could ever really talk to him about it either." So no one really know how he felt about it.
"The Kingdom has not celebrated it since then," Namine added. Most everyone knew when it was, but it was little more than a day. "The servants usually even try hard not to treat him specially on that day, lest we draw attention to his misery somehow." It was very sad, really.
The Princess reached over and put a hand on Riku's for a moment. "If you could do something for him, I think you would be the one to do it. I so wish that we all could, but I am afraid of upsetting him."