After re-watching Mr. Robot I have a theory, Christian Slater is Rami Malek’s alternate personality / figment of his imagination. Malek says Slater isn’t allowed to smoke on the Subway platform, Slater does anyway, because he’s not there. None of the other hackers even glances at Slater. They’re all looking at Malek, because they see him talking to himself, and it’s weird but they’re also used to it. The whole goal is to destroy the corporate consumer credit records.

This is Fight Club reimagined.