There is an event when you visiting the church after they come back from the Vatican, Shanice will talk to you about how she feels about PriestBot, and after that when you go for a walk, there should be an event where you met PriestBot and there will be 2 choices for you to choose.
- Tell him the truth and tell him to go talk to Shanice.
- Don't tell him anything and lies.
If you're being honest with him, he will come along in the Investigating the Burnt Lab event.
If you lied to him, then he won't come with you and you will get a bad ending.