Upstairs, Downstairs/WMG

Alfred is autistic
His speaking predominantly in scripture is a form of scripting (a behavior that's a common symptom of autism), plus a lot of the things he says sound like they could have come from Mr. Hudson or Pierce. Plus, problems sleeping can occur along with autism, and it could explain why he terrorizes Sarah in the first episode by quoting at her and grabbing her wrist, yet no-one else is bothered by his behaviors and simply says he's "a bit touched in the head", and by the time of "Board wages" she clearly sees no reason to be afraid of him, suggesting he didn't actually mean to do her any harm.