Just into its second season, “Preacher” has been no stranger to tragedy. The AMC adaptation of the Garth Ennis comics series has touched on lost pregnancies, revisited parental abandonment and unleashed a citywide explosion that wiped away most of the first season’s recurring characters.

But Monday night’s episode, “Damsels,” may have seen the show at its most heart-wrenching. Watching a frightened Eugene attempt to replace the violently displaced brains of his high school crush Tracy Loach — and have the same shotgun be the source of Eugene’s infamous facial scar — was a twisted answer to one of the show’s biggest looming questions.

It’s a scene that Ian Colletti’s been preparing for, ever since getting the part. “As an actor, so much of your time is spent off camera in your preparation, meditating on your backstory and filling in the puzzle pieces. It’s very rare...