He didn't believe it. He couldn't believe it, because that would mean giving up his – his whole family, basically. He paused at his portrait in the now empty room, struggling to maintain his composure and dignity. It was difficult; he'd never felt anything so potently aching. But he managed, like he always did, and took a deep breath before plunging into the depth of the house.
Walburga's portrait by the door was one he avoided at the best of times. The miserable bat had a fine pair of lungs even as a painting and wasn't afraid to use them. But this wasn't the best of times. He burst into the frame beside her, causing her to screech and stumble. He ignored her as her curtains burst open and she began to wail. There was no one in sight, not even the old house elf.
He had the same luck with the other three portraits in the house. But no, it couldn't be because of what...because of what the Potter boy said had happened. He couldn't even think about it. His mind refused to. He raced back to his portrait, calling this time, as loud and as frequently as possible. The name echoed through the house, right back to him, and by the time he reached the empty room, he'd realized that it was true. He leaned against the portrait frame and called the name one last time: "Sirius! Sirius Black…"
But there was no answer, and at last, Phineas Nigellus had to give in to the fact that his grandson was dead. And with him, he'd taken the whole Black legacy. With him, he'd taken the last thing Phineas had.