A community formed around a single shared enthusiasm reliably divides into hostile groups. The pattern repeats across entirely unrelated subjects, which suggests a structural cause rather than a cultural one.
Shared enthusiasm is not shared interpretation
People drawn to the same work arrive for different reasons, and those reasons produce incompatible expectations about what it should do next.
While the work is still arriving, each new instalment either confirms one reading or contradicts it. Every release is therefore a test that some members fail.
Disagreement is built into the situation from the beginning and only becomes visible when the work resolves something.
Belonging has to be demonstrated
Membership in an online community is established by visible signals, since nobody can see how much anyone actually cares.
Knowledge, longevity and intensity of opinion all serve as evidence, and stating a position more strongly is the cheapest available signal.
That produces steady escalation, because a moderate position demonstrates less commitment than a firm one and is read as weaker attachment.
Platforms reward conflict mechanically
Disagreement generates replies, and replies are treated as engagement, which increases distribution.
An argument therefore reaches more people than an agreement, and the most contested positions become the most visible ones in a community.
Newcomers encounter the loudest disputes first and reasonably conclude that these represent the community, which is how a small argument becomes the group's identity.
Small differences do the most work
Factions form around distinctions that are unintelligible from outside, because the shared ground is assumed and only the differences are worth discussing.
The more a group has in common, the finer the distinctions it will find, since identity requires something to distinguish.
This is why disputes inside a fandom are frequently more bitter than disagreements with people who dislike the work entirely. An outsider is not competing for the same standing and can be ignored without cost.
The object stops being the subject
Mature factional disputes are usually about the community rather than about the work, concerning who is a real fan and whose reading is legitimate.
At that point the work itself becomes a token in an argument that no longer depends on it, and new material is read for what it does to the dispute.
Communities that avoid this generally do so through active moderation and structure, which is a maintenance task rather than a natural state. Left alone, a large fan community drifts toward argument because argument is what the surrounding systems reward.