Those of us who are in fandoms can get so used to living in a world full of gay fanfiction that we begin to forget where it all started. People didn't start shipping seemingly diametrically opposed male characters with Harry and Draco or Sherlock Holmes and John Watson in the 2000s. It all goes back to Kirk and Spock.
Some scholars believe that the Kirk/Spock is the oldest slash pairing in modern history, and that makes a lot of sense! People have been writing fanfiction about those characters getting together since the 60s, and it hasn't slowed down since. Whether you or I find the pairing weird is completely irrelevant. When I watched Star Trek: The Motion Picture, it didn't set off any alarm bells in my mind that these two were more than friends. But fanfiction is a creative and interesting way of engaging with the source material, and I would never yuck anyone's yum. If you like to engage with this fandom through memes, these Star Trek memes might be a better fit.