Sidekick Season: Why Secondary Characters Always Get the Best Alternate Universes

Here's something you've probably felt without being able to name it. You're scrolling through an AO3 tag or a comic event tie-in, and the most electric, genuinely surprising alternate universe story you find doesn't star the main character. It stars their roommate. Their nemesis. The background figure who got exactly four lines across three seasons and somehow has a 200,000-word canon-divergence epic where they became a revolutionary, a villain, a god, or all three.

This isn't a coincidence. It's a pattern so consistent across fandom and official media that it practically qualifies as its own narrative law. And once you see it, you can't unsee it.

The Protagonist Problem

Main characters carry enormous narrative weight. That's kind of the whole deal — they're the load-bearing walls of their stories. But that structural importance becomes a trap the moment you try to imagine them living differently.

Take almost any major franchise protagonist and ask what their alternate universe looks like. What you'll usually get is a version of the same story, slightly remixed. The chosen one who wasn't chosen, but still kind of was. The hero who lost earlier, but still ended up heroic. The character who made a different call at the critical moment, but whose fundamental arc bends right back toward the same destination.

There's a reason for this. Protagonists are defined by their story function. Strip that away and you're not exploring their potential — you're just writing a different character wearing their face. Audiences sense this, even when they can't articulate it. An alternate-universe Peter Parker who never got bitten by the spider still feels like a story waiting to become Spider-Man. The gravitational pull is too strong.

Supporting characters don't have that problem. They were never the center of anything. Their futures are genuinely open.

Where the Real Freedom Lives

Think about the characters who tend to dominate fan-created multiverse content. The sarcastic best friend who exists to deliver exposition and emotional support. The villain with a tragic backstory that got two scenes of development. The mentor who died to motivate someone else. The rival who lost the big match and then mostly disappeared.

These characters have defined personalities, established aesthetics, and emotional hooks — but they don't have narrative destinies locked in. When a fan or creator asks "what if things had gone differently for them," the answer can genuinely be anything. The best friend could've been the one with powers. The villain could've had their redemption arc go somewhere unexpected. The mentor could've survived and made completely different choices.

There's no predetermined ending pulling them back. The multiverse, for these characters, is actually infinite in a way it rarely is for protagonists.

Fan Communities Figured This Out First

Fanfiction communities have understood this dynamic intuitively for decades. The most celebrated alternate universe works in major fandoms — whether you're talking Marvel, Star Wars, anime properties, or long-running TV shows — disproportionately center secondary figures. Loki got richer alternate-universe treatment from fans for years before Marvel made it official canon with a whole TV series. Zuko from Avatar: The Last Airbender has an entire ecosystem of AU stories that dwarf what exists for Aang. Characters like Crowley from Good Omens or basically anyone from the supporting cast of Supernatural built massive alternate-universe followings while the leads stayed relatively fixed in their roles.

Fandom is essentially a distributed research-and-development operation for narrative potential. When millions of creative people independently gravitate toward the same characters for their most ambitious worldbuilding, that's data. And the data keeps pointing at the sidekicks.

When Official Media Finally Catches Up

What's interesting is watching how official properties have slowly started responding to this. Spin-offs, anthology series, and tie-in comics increasingly focus on secondary players precisely because creators and studios have noticed where the fan energy lives. The Andor series in the Star Wars universe is a good example — Cassian Andor was a supporting character in Rogue One, and his solo story became arguably the most critically acclaimed Star Wars content in years. The freedom to tell a genuinely different kind of story came directly from not being beholden to the main saga's gravity.

Similarly, the multiverse-heavy phase of the MCU generated its most interesting character work not with Tony Stark or Steve Rogers variants, but with characters like Sylvie — a variant of Loki who existed entirely outside the original's narrative weight. The alternate universe gave her room that the original timeline could never offer.

This isn't always intentional. Sometimes studios stumble into it. But the pattern holds.

The Emotional Investment Equation

There's also something psychologically interesting happening here. Audiences often feel safer investing in secondary characters' alternate lives because there's less at stake emotionally. If an alternate universe version of the main character goes somewhere dark or strange, it can feel like a violation of something beloved. If a supporting character's AU gets weird, experimental, or tragic, it reads as exploration rather than corruption.

This gives creators — both fan and professional — more room to actually take risks. The best alternate universe storytelling requires genuine stakes and genuine uncertainty. Secondary characters provide that in a way protagonists structurally cannot.

There's also the underdog factor. Part of the appeal of imagining richer lives for sidekicks and secondary players is a kind of narrative justice. These characters were interesting enough to remember, but the original story didn't give them space. Alternate universes become a way of correcting that imbalance, of insisting that their potential was always there and deserved more.

What This Means for Worldbuilders

If you're building your own multiverse — whether that's a fanfic, an indie comic, a tabletop campaign, or an original fiction project — this pattern is worth taking seriously. The characters who will generate the most imaginative alternate-universe energy probably aren't your leads. They're the ones in your ensemble who have strong personalities and clear aesthetics but whose futures remain genuinely undetermined.

Give those characters just enough definition to be compelling, and then leave their horizons open. The audience will do the rest. Or you will, in the quiet hours when the main plot feels stale and some secondary figure keeps tugging at your attention, asking what would've happened if things had gone just a little differently for them.

The multiverse belongs to everyone. But some people have been waiting longer for their turn than others. And honestly? They've earned it.