- Fans of the anime tend too easily to accept Koizumi's theory that Haruhi is God. Koizumi himself doesn't present it as certain fact; he labels it as a theory and a "worst case scenario" that his Organization is acting on.
- Ironically Koizumi is the one source we know is unreliable. The acceptance of his version comes from one of the alternatives being Technobabble and the other so heavily redacted as to be meaningless.
- Also often accepted as true is the idea of Koizumi being gay, despite the fact that this has never been confirmed in canon. In fact, there is some evidence that contradicts it. In one of the novels, Koizumi says that he only acts the way he does because Haruhi expects it and would make him that way if he didn't, which fans have interpreted as referring to the Ho Yay between him and Kyon, but it's more probable that he was talking about his Yes-Man behavior towards Haruhi.
- Another example is the Fanon OTP of Kyon and Haruhi. This is likely due to three factors. 1. The rather popular anime is missing a lot of narration that counters the Kyon/Haruhi pairing, 2. The first novel and some of the second, which accounts for the larger part of the anime, tend to focus on that pairing, but the later novels, which tend to not, haven't been adapted yet, and 3. Since the first novel is very Kyon/Haruhi oriented, much of the evidence in the later novels contrary to this pairing tends to be hand waved or used as confirmation bias. It's rather shocking how insistent people are that this is the official couple. It should be mentioned that this is no mere ship. Many Kyon/Someone Else and Haruhi/Someone Else fans will claim that Kyon/Haruhi is actually the official couple, but ship them with others anyway.
- Many fans are also convinced that Mikuru is actually a manipulative girl sent to the past specifically to appeal to Kyon. This is never confirmed in any way (or even mentioned after Koizumi throws the idea out there) and in fact what little character development Mikuru has gotten so far seems to suggest that she is actually not very confident in her abilities. This fanon is due to Future Mikuru being a bit manipulative.
- Although not universally accepted, a popular fan theory is that Kyon is the real Reality Warper, not Haruhi. This is supported by many things, including the statements in the first episode/first chapter that he was once as eager to find supernatural beings as Haruhi.
Fanon / Haruhi Suzumiya