Frazzled, Regulus hurried toward the group, grateful to see familiar faces in the crowd; to say he was unsettled by the Inferi attack was something of an understatement, but he had held his ground and fought rather than turning tail and running as his survival instincts had urged.
As soon as he saw the first shambling creature, his mind went straight to Bellatrix, and he had little doubt she was behind this attack, which meant he wanted nothing more than to put as much distance between himself and her as possible. But then anger had risen within him - anger that she had tried to turn him, her own flesh and blood, into one of those things; anger that she had terrified him so much that he had been living in fear ever since - and he had let his anger sweep him into the fray.
Eventually, he spotted familiar faces, and he made his way toward them, panting, sweating, and disheveled, but inordinately pleased with himself for standing his ground against Bellatrix, even if it was indirectly.
"Fancy meeting you here," he said, greeting Harry, who was closest to him, with grim humor.