Character Analysis
To Be or Not To Be
Oof. The question of Sammy Jankis is mind-crushingly confusing.
Is Sammy Jankis Sammy Jankis, or is Sammy Jankis Leonard? And is Mrs. Jankis Mrs. Jankis, or is she Leonard's wife? Or are they…
Oof. Oof again. Of all the conundrums that Memento poses, the question of the Jankises is the most intensely hard.
Let's simplify here for a sec. We're going to start with the assumption that Leonard's memory before the incident is intact and that Teddy is a rotten liar… neither of which is too far-fetched. In this case, Sammy acts as a parallel to Leonard's own life and Leonard uses Sammy's story as a way of thinking about his condition. Sammy wrote haphazard notes and couldn't learn through conditioning, but Leonard is very organized and is able to train himself through routine, essentially circumventing the need of memory. This is the Sammy that Leonard tells people about to help explain his condition to them.
What's interesting about the Sammy Jankis story, however, is that there are a lot of little details that don't quite line up. Did Sammy really make a bunch of unorganized notes? We never see them. Why can't Sammy learn from conditioning? Why isn't there physical evidence of Sammy's memory impairment? All of these things are strange details that don't necessarily give us any insight into Leonard's own story unless we consider an alternate possibility—suggested to us by Teddy— that Leonard has actually combined his own past with a separate identity (that of Sammy Jankis) as a coping mechanism.
If this is actually the case, then Sammy is nothing more than a case that Leonard worked on way back when. Sammy was some faker looking for insurance money, and he didn't even have a wife. All of these details about Sammy's poor notes, inability to learn from conditioning, and his diabetic wife are details of Leonard's own past. Leonard's diabetic wife survived the assault but couldn't live with Leonard's brain damage and, in a last ditch effort to revive the real Leonard, had him kill her with an insulin overdose.
Nobody Knows
But just because Sammy is very briefly replaced with Leonard during the care home scene, that doesn't mean that the Sammy = Leonard hypothesis is true. Maybe there was a Sammy and maybe there wasn't.
While the existence or nonexistence definitely matters to Leonard, it matters less to us. Sammy and his wife illuminate a lot of things. They show us how smart and efficient Leonard is; how objective he can be about things and how difficult it is to function normally with retrograde amnesia. They call into question the reliability of memory, just as Leonard did during his meal with Teddy. They question the subjectivity of reality and how we can create and distort what we think is real.
They basically just throw all certainty to the wind. At the end of the film, there is really no way of knowing if Leonard is lying to himself or if Teddy is lying to him. But this lack of certainty is just Nolan messing with us; it's Nolan forcing us to feel the same way Leonard feels about everything.