Teddy is actually a cop because HE DOES carry a gun into the isolated building in the scene when Lenny kills Jimmy, and Lenny hits him on the back of the head and then takes the police badge and the gun proving that Teddy is indeed a cop
I think Teddy actually is the 2nd attacker Leonard has been looking for and every time he gets close to identifying his John G., Teddy manages to misdirect him and put Leonard on the scent of someone else, usually by manipulating him over the phone.
The delicious irony of this theory is that Leonard does finally get the real John G., even though he ends up manipulating his own memory to do it.
Very sharp. I've said this since the beginning. I recognize that Leonard's first tattoo could also have been a lie, directed at John Gammell.
And, good catch on Teddy obviously lying about his being a cop. He even thinks about stealing Jimmy's shoes!
This film has some really different theories out there. Some of this thread still makes me laugh. The backbone is still there under all of these layers. The truth remains. Quite the accomplishment by the Nolan brothers.