"Sunlight knew the monster he was." On some level, whether conscious or not. Maybe he'd wanted to frighten Scully with an image of evil lurking, but his control over what Scully saw couldn't have been such that he'd orchestrated the details of the vision.

And then she speaks again, and it's everything he never would have expected. Mulder looks at her, taking in that momentary distance in her gaze as it sharpens into the here and now. "What did you see, Scully?"