Throughout the movie we, along with Leonard, believe a skewed view of events. In his mind, one night his wife was attacked by two men, one of which he killed, but the other cracked his skull and escaped. His wife died and he developed his memory condition. The police didn't believe his story of a second attacker, leading to him, with the help of a cop, starting to hunt down the mysterious John G. That's not quite the truth. The attack on his wife (suggested to be junkies too high to realise they were breaking into a house with two people) did happen, with the same conjecture over the number of attackers, but the hunt wasn't instantaneous, mainly because his wife didn't die then. She died later on of totally unrelated circumstances (which will be fully expanded on in the next point), meaning the whole mission Leonard's on is motivated by skewed facts. Here's where one of the key themes in the film comes into play; the role of memory. Leonard himself says mid-way through the film that "memories can be distorted. They're just an interpretation," which is evidently happening here; the sight of his wife under the shower curtain has developed so she appears to not be breathing. A couple of times in the film Leonard delivers by rote a statement of "who he is", which is described by Teddy as "who you were". Obviously on a basic level this is commenting on how the hunt for vengeance has changed him, but with what we're seeing "distorted", it's actually looking closer at how much who we are is defined by our experiences; if Leonard's memories are being altered then at what point does he become a different person?
