Sora gave Riku a face when she wasn't looking for a second. SEE?! She's like...???
The Prince sat down and noticed that other people had noticed him escort her to the table and upstairs, and were occasionally glancing up there. He hoped that either his sister or Lady Belle would come soon.
Now the Prince was fairly certain that Tohru hadn't ever met Riku before. "Riku, this is Lady Tohru of Mire," he introduced. "Lady Belle of Mire's younger sister." Even though he already knew that.
She also had not been at the keep, nor had she spent much time with her sister yet, so it startled him just a little that she was able to identify Riku so right away. "The what?" He asked curiously, as if he didn't know. "You have heard of Riku already?"