It's not obvious on how you meet him. In later updates you will meet him on either route you start, however I hadn't yet implemented him into the Silas route. In order to get on his route you need to lie to Silas and have a charisma of 10 (the lowest you can have). In order to make sure you have the right charisma, don't choose "love", "a lover" or "friends". If Silas doesn't offer you a ride then you're on the right track.