I just had a thought.
When Patrick first appeared, he seemed manipulative and in control.
Lately, Patrick's been unstable and all bibbly.
How do we know that's Patrick? Could there be another alter in the Michael/Patrick system? Patrick has imitated Michael, so why not a third imitating (or at least claiming to be) Patrick?
I see Occam stropping his razor over there, so let me try another version. What if unstable-Patrick is actually Michael (who is historically the emotional one) and seemingly sane Michael is Patrick?