Sora wasn't used to showing affection outwardly, so it was just different and odd to him, but he was happy to oblige Riku when he knew he was panicking inside.
The Prince gave Riku a gentle squeeze and rubbed his back a little. "Riku, you are alright." He assured him. Corin wasn't going to grab him or yell at him again. If he did, Sora would be kicking him out of the room real fast.
Sora shook his head a little. "I cannot really speak for what he is feeling but...I know that sometimes processing even positive emotions and situations can be overwhelming when you are not used to it." He moved a little to adjust his hold so he could see Corin better.
He didn't feel entirely comfortable telling some of this stuff to Corin but...if it helped him understand Riku better at all... "As Prince I am not proud to admit this but, I did not get along well with others my age for most of my life. So, even being invited to a small gathering, for me, makes me worry and panic so that I just want to hide away from everyone all day." Even though it was a positive thing, a fun thing, something he should be excited about. He shrugged a little again, not able to be of much more help than that.