The Division is baffled by the death of a woman from a disease she apparently never had. Meanwhile, Olivia does her best to keep the secret about Peter to herself.

the return of Kevin Corrigan's "mystic bowling alley guy" character.

The more I think about that "Walternate as the bad guy" hypothesis, the more it makes sense to me. But if Walternate IS the bad guy, then the writers missed a golden opportunity IMO to begin building that sub-plot into the story arc.

Sicky Boy had just spilled his guts to Olivia, mentioning more than once a "mysterious stranger" whom he had met at the hospital years ago. Now, when Peter and the cops arrive, had the writers simply included Walter in the arriving party - simple enough to do, all they need is to have some plausible excuse for Peter to be driving somewhere with Walter in the car after midnight. Sicky Boy recognizes Walter and says something accusatory. Walter, of course, has no idea who this man is, because he never met him at the hospital - Walternate did. The writers only needed to stick Walter in Olivia's apartment to begin laying the groundwork for a Walternate Reveal in 3 weeks.

It would've been too easy, but they didn't. Which makes me tend to think that Walternate ISN'T the bad guy.