Louis always forgetting small things, like when he set something down, when he put food on the stove, when he started running the sink or the shower.
Louis not thinking anything of it, until it happens more and more. Louis starting to question the pattern of events that got him here, into Armand’s pent house that he can’t leave, with books he can’t reach, and nature too many floors away.
Louis deciding to call David insisting he needs to tell his stories again, because the tapes don’t sound right, and nothing sounds right anymore.
Armand agreeing, and Louis doesn’t see the glint in his eye. The next morning Louis’s bath overflows and he still can’t find his book.
I feel like many people have a fundamental misconception of what unreliable narrator means. It's simply a narrative vehicle not a character flaw or a sign that the character is a bad person. There are also many different types of unreliable narrators in fiction. Being an unreliable narrator doesn't necessarily mean that the character is 'wrong', it definitely doesn't mean that they're wrong about everything even if some aspects in their story are inaccurate, and only some unreliable narrators actively and consciously lie. Stories that have unreliable narrators also tend to deal with perception and memory and they often don't even have one objective truth, just different versions. It reflects real life where we know human memory is highly unreliable and vague and people can interpret same events very differently