Alex's process of meeting Ryan was relatively simple - step one, stir up some trouble; step two, meet face to face.
After talking for a while, Ryan agreed to join Alex. It wasn't that Ryan was easily trusting, but those child of the era tended to feel a sense of connection with others like them. That was one reason why their cooperation succeeded so quickly.
The other reason was that the paths both of them intended to walk were remarkably similar, making it easy for Alex to persuade him.
If Alex had come with the intention of destroying the world, he wouldn't have been able to leave this place today.
Though Ryan wasn't one to kill, he wouldn't hesitate to beat someone to the point of being crippled. After all, crippling someone wasn't the same as killing them.
Once they finished discussing the future of their power, Alex shifted the conversation to finding someone.