Apprehension filled Harry, squeezing his heart painfully. His dad....looking like the shock was extremely unpleasant. Instinctively, Harry knew how he must feel...the same way Harry himself had when he saw Al all grown up, past those years that Harry wanted to cherish. Missing his son's childhood was heartbreaking.
Nervously, he pushed his glasses up his nose in the characteristic gesture, feeling at a loss. He wanted to hug his father, but it wasn't as easy as it was with his mother. She was so open with her emotions, so clear. James Potter was the more serious one.
"It's me, Dad," Harry managed, although his voice cracked on saying dad. It was almost too much. "I...I know this is strange, and there is a lot to explain to you but..." He gestured helplessly. "The patronuses...I mean, I want you to believe me but I will understand if you need to...test me. Somehow." He smiled, very briefly, thinking how absurd that was, but it faded as he waited, desperately, for his father's approval.