Intelligent, certainly. Loyal, also certainly. Brainwashed? Aziraphale seemed about half and half. He was stuffy and serious, but had enough of a sense of humor that Gabriel had hope for him. The fact he'd actually disobeyed orders, actually questioned, was what sealed the deal, as it were. Aziraphale was a brother Gabriel could invest in.

Though maybe not in ways Balthazar was thinking.

The archangel snorted. "Well, let's see, bro: I was killed by Lucifer and then I woke up here. The linearity of time indicates something coming after your life has ended is called an afterlife."