Maybe it's the knowledge of what's become of him that has him clinging to Cassandra back, or perhaps Percy is still reeling from all the lost time they've had, from when Percy had been convinced that she hadn't survived that initial attack on Whitestone by the Briarwoods. Either way, it seems like both the de Rolo siblings are clinging to each other.

"Yes, I thought it strange that I've simply understood everyone's speech so far." Sure, Common was nearly universally used wherever he went, but there would occasionally be smatterings of Elvish and Dwarvish mixed in. "A neat trick, though. That would have been handy over the course of our adventures."