Horvath is, by and large, a fairly stoic figure. He's weathered the closing of the portals, the winter storm, and numerous injured people with nothing more than possibly a raised eyebrow and a few weary sighs. There is a strong impression that he has been around and suffered through some terrible dark times before, and while he's not enjoying any of this, it's not really new and he intends to simply put his head down and work to get people through this as well as they can manage.

The Morganian pentacle appearing nearby gives him a start though, and for the first time since returning to the Nexus he looks genuinely alarmed. It does not quite break his concentration, but the rubble that he's currently holding up falters and shifts a little, which is not helpful, but not bad enough yet to be disastrous.
After a quick glance around for attacking sorcerers, he steadies, and eyes the grey figure for injuries because if they're okay they might be able to help rescue others.

"Perhaps we'd best make sure the boy who went downstairs is all right..." Even as he's suggesting this to Hermione, the penny drops. The boy did have a ring, didn't he.