The Doctor pulls a face. And his blunt honest comes out. "I hated kids like you in school."

Just saying. He was a lonely little boy for a lot of reasons. And children like Adrien didn't help matters. But it's not said with bitterness, more like reflection. An insight into his life that would normally not be spoken aloud.

"How do you define yourself?"

Because he can tell that there might be some differences.