Percy had been wondering if Cass would come back with Aiden. No matter what Cass said, he thought that it would be safer if Lestrange didn't know that the boy was his son, and hoped that maybe she'd change her mind when she found out.
That was dispelled the moment Cass opened the door, and Plato started barking, and it was different from his usual greeting. "It's okay, boy," Percy said. "Quiet now." He cast a spell to create an invisible barrier so Plato wouldn't run and overwhelm Aiden.
He walked to the hallway, and he smiled at Cass, wanting him to know that he wouldn't do this alone and then he looked at the boy. Good thing he had been partially prepared thanks to the picture, but that red was so much like his own. "Jesus," he murmured, before shaking his head and stepping forward. "Hi, Aiden, I'm Percy Weasley," he said, stretching his hand toward the boy. "Welcome."