Adrian had brushed off the similarities thinking there was no way two people he knew could be telepaths right up until Ivy randomly started "hypothetically" speaking about Doctor Y in front of the movie theater.
She even went as far as saying she wouldn't want someone inside her head. Very funny.
He played along with her as she posed questions about a person Doctor Y couldn't hear without them even realizing it. If such a person existed it wasn't him. He was actively blocking his thoughts from being accessed even if it was aimed at someone else.
Her allusion to someone like him was suspicious but he wasn't 100% certain she was actually a telepath yet. That confirmation didn't come until the thought 'I should buy Ivy Sour Patch Kids' popped into his head.
There was a distinct flavor to thoughts that hadn't originally come from him. Goodness knows he could recognize how it felt by now.