Riku was surprised, really. The Prince was a very romantic soul. He loved sweet words, but also loved to show his affection in sweet and unexpected ways. Perhaps he got it from all his reading.
The story about the scarf was more along of what he wished to hear about though. It brought a smile to his face that made him feel like he was in on an older story... knew the punchline of the joke so that he would be prepared the next time it was told. It was a wonderful feeling of being included.
"That is incredibly adorable," Riku said, "I bet the two of you were endearing children. I wonder if my parents have any such thing of mine." Some kind of poor attempt at creativity that was kept solely for sentimental reasons.
"Master Zexion has been here that long? He does not act like he is an old man." He was very sharp, and very quick.