Spider-Man, as far as we currently know, isn't bisexual. There has been no canon confirmation either way about it. Many people get very, very upset at the mention of anything pertaining to a non-heterosexual Spider-Man. However, at the same time, there seems to be a pretty vocal subsection of the LGBTQ+ comic fandom that wants to see Peter Parker get a boyfriend (or at the very least, feel attraction toward a man). And it doesn't have to be the Earth-616 Spider-Man -- there's an entire multiverse of Spideys to choose from.
But why, out of all of Marvel's supposedly straight heroes, has Spider-Man in particular attracted this kind of speculation? There are already a few out and proud characters in comics, as well as characters who have a lot of relationships teased in the pages of them (Kitty Pryde, for example). So, why is Spider-Man -- or, rather, "Bi-Derman" -- such a popular headcanon among LGBTQ+ comic fans?
WHEN THE SHIP FIRST SAILED
The practice of shipping has existed for a long time in fandom. Properties and universes with tons of characters invites to the shippers mixing and matching all sorts of disparate characters up, regardless of whether or not they'd make for a logical match in the eyes of others.
In this case, it is important to differentiate shipping from the core idea of bisexual Spider-Man. Fans have shipped Spider-Man with other male characters for years before. The Hugo-Award Winning fan fiction site, Archive Of Our Own features stories pairing Spider-Man with Johnny Storm and Harry Osborn that date back to 2002.
Over time, more online support for Peter Parker getting a boyfriend developed. Out of the thousands of works just listed on Archive of Our Own, Peter's most popular slash (same sex) pairings include: Tony Stark; Wade Wilson; Ned Leeds (presumably, the MCU version of Leeds), and Steve Rogers. This is compared to the surprisingly low number of works where Peter Parker is shipped with Michelle Jones, the most popular straight ship.
It doesn't hurt that many of these ships have representation in the comics. The earliest ships with Johnny Storm and Harry Osborn play on the fan obsession with best friends becoming lovers, and arch enemies to lovers. Once Deadpool, who is canonically pansexual, entered Peter's life, however, the shipping only increased. This wasn't hampered by the fact that Deadpool isn't shy about expressing his attraction to Peter.
Still, shipping is one thing. A lot characters become part of popular ships. How did Spider-Man rise to become a queer icon today?
THE GARFIELD EFFECT
LGBTQ+ representation remains surprisingly uncommon in superhero comics to this day. For all the discussion of improved representation, there are very few good examples of it -- and even less so when characters make the jump to the screen. The first noteworthy example of clear(ish) LGBTQ+ representation in a superhero film was in the 2017Â Power Rangers movie. Sure, characters who are bisexual in the comics did appear on screen -- Mystique, Catwoman, Wonder Woman, Harley Quinn -- but their bisexuality has, so far, been either erased or barely present. It's also noteworthy that the vast majority are women.
Enter The Amazing Spider-Man franchise, which came to be a lightning rod for the representation discussion. Early on, when the first film was announced, fans petitioned Sony to cast Donald Glover as Spider-Man. Obviously, the role went to Andrew Garfield, but the discussion that Spider-Man can be anyone was given increased visibility from there. Not long after Miles Morales appeared on the scene. One of Morales's creators, Brian Michael Bendis, referenced the petition for Glover to be Spider-Man as a source of encouragement while developing Morales.
Speaking at a convention, Garfield once speculated that Peter Parker could be bisexual. If one fan petition supported the need for a black Spider-Man, why couldn't fans help increase support the creation of a queer Spider-Man, too?
PETER'S TWO DADS
The following subsection of queer Spidey "fanon" is an an intersection of several other fan ships and pairings that built up to the creation of Bi-derman.
A very popular ship among some Marvel fans is Tony Stark and Steve Rogers. Due to this, Tony Stark's recruitment of the young Peter Parker in the MCU led to many fans who also shipped Tony and Steve seeing the development as an opportunity to create a faux-family out of their ship, with Steve and Tony being Peter's adoptive father, tying Peter even closer to the queer community.
It didn't help that the movie that introduced Spider-Man to the Marvel Cinematic Universe, Captain America: Civil War, featured a ton of moments that Steve/Tony shippers lapped up.
On Archive of Our Own, there are 1435 fanfics tagged "Steve Rogers/Tony Stark" just within the Spider-Man tag. This might seem unimportant in the grand scheme of the Archive's size, but it helped strengthen the groundwork for Peter Parker being tied to a queer identity without him actually being paired up with a man. He's simply surrounded by LGBTQ+ friendly ideas.
Other fans, especially on Tumblr, have also expanded on the idea of a Rogers/Stark/Parker family unit: illustrating fan fiction with fan art.
https://artemisbastet.tumblr.com/post/79512291302/day-trip-to-the-superfamily-not-my-drawing
VIRAL BISEXUALS
What is thought to be the earliest viral post about Bi-Derman (as in, not a ship, just a romantically unattached bisexual Spider-Man) was a tweet from @whizzwhozz: "BI-DERMAN, BI-DERMAN, DOES WHATEVER A BI-DERMAN CAN, KISS A MAN? SURE WHY NOT, ALSO HE THINKS GIRLS ARE HOT, LOOK OUT, HERE'S COMES THE BI-DERMAN."
The tweet itself retweeted a funny observation made by @instertellar about the way that Tom Holland's Parker wears his jeans: "peter cuffs his jeans yall know what this means."
What's interesting here is that Spider-Man isn't kissing any men in this shot -- or even sharing the screen with any. The observation just play off of in-jokes in the bisexual community. The source of the tweet, which draws attention to the "cuffed jeans," is a fairly common one.
As such, many fans took this queer coding even further, and the viral tweet soon inspired a meme among the LGBTQ+ community that Spider-Man was a "disaster bi." Unlike prior fan efforts, this didn't depend on Spider-Man being shipped with any men, but rather just him embodying traits they saw internally about themselves and other members of the community.
Spider-Man has always been a character defined by bad luck and misfortune. He is an absolute disaster, by many metrics. This adds to his universal appeal: everyone can relate to feeling down on their luck. The bisexual community simply applied the old Parker Luck to their own experiences. Thus, support for Bi-derman snowballed.
The memes started to spread. Fast.
https://thebeesandthebis.tumblr.com/post/178378606228/a-little-bi-derman-for-bi-visibility-day-happy-bi
https://ameeg.tumblr.com/post/187128848419/omg-its-him-its-bi-derman
https://cryoverkiltmilk.tumblr.com/post/187619966199/i-read-this-and-immediately-had-to-make-this
WHAT DOESN'T KILL YOU MAKES YOU STRONGER
All of this was just a spot of fun, of course. However, in many respects, what made fans more adamant about bisexual Spider-Man was the immediate backlash. A small but vocal portion of fans are against the diversification of iconic characters, acting as though, by a character coming out as part of the LGBTQ+ community, that something that "belonged" to them is taken away. This backlash was very apparent when Bobby Drake came out as gay.
Even with canonically bisexual characters, fans are often in denial about it if this aspect of them isn't referenced every waking second.
Tom Holland has said -- more than once -- that he is open to the idea of a gay Spider-Man. The backlash to this announcement was immediate and harsh, that Spider-Man can't be queer because he's always been straight.
The core criticism that a bisexual Spider-Man erases decades of history of the character dating women erases what being bisexual is: dating men, women or gender non-conforming people. A bisexual Peter Parker can easily date Mary-Jane, for instance, while still being bisexual. And even if the character started to identify as gay, as we learnt from Ice Man, it's never too late for a character to come out of the closet. That's something that's also true to life.
Of course, rather than snuff out the fandom, this sort of resistance makes it more powerful. The LGBTQ+ community has always been put down upon. Spider-Man has always been put down upon. Rather than scare people into not supporting it or shout them down, opposition only makes people want to talk about it more.
In some ways, intense reactions on either side are be expected for a character as beloved as Spider-Man. But for those simply asking to see themselves represented in the media they love, it's good to remember the famous words of Peter Parker's fan-appointed father: when the world tells you to move, you plant your feet firmly and respond, "No, you move."