Ron, who was pretty sure he was going to be skinned alive once his Mum figured out they'd gone off somewhere, shifted a bit nervously as they apparated inside Grimmauld. The place was creepy, and considering some of the creepy things Ron had seen, that was really saying something. His fingers tightened around his wand when Hermione went rushing off, muttering under his breath about house elf's heads and needing to add one to the collection.
He thought they'd all been a bit dense, with the answer right in front of them, and that great bloody family tree in the house that they'd all seen.
He caught up with the other two just as Kreacher began to cry, his jaw dropping in shock. He'd never seen a house elf cry, and one as old and as unpleasant as Kreacher, well it wasn't a pleasant sight, not to mention it made him feel faintly guilty for no reason he could determine. It wasn't as if he'd taken the useless bits of junk.
"Ugh. Mundungus, of course. How the bloody hell are we going to track him down?" It just figured. They finally got close, and once again, someone had got there before they had.