But what if there is nobody like you in the books you read or the movies you watch?
It's not just that explicitly autistic characters in fiction are few, but that when they do exist they're sometimes little more than clinical criteria squeezed into the shape of a child to give the neurotypical characters something to bounce off. Or they're genius savants, which relatively few real people on the spectrum are, or they're monsters or changelings or other mysterious Otherish creatures. Realistic, sensitively-depicted autistic and Aspie characters do exist, but are mighty light on the ground.
Fortunately, there are any number of characters that aren't explicitly on the spectrum but display enough autistic tells that we can take them and claim them as our own. They might have been written as Aspie in the first place, it might have just happened by chance, it might be obvious or you might have to squint and use a bit of creative interpretation, but fan-diagnosis of fictional characters is alive and well.
Why fan-diagnose a character? Can't we enjoy them without trying to presume their neurology?
Well, why not?
Identifying with fictional characters is valuable. Even leaving aside the sheer enjoyment to be gained, it can teach empathy, and affect the way we see ourselves and even our physical abilities. If we're identifying with the sort of characters we'd like to be in real life, it can bring us a bit closer to being better human beings. It's also a form of validation: the inclusion of people like us in popular culture is a cultural acknowledgement that people like us deserve to exist. If that acknowledgement isn't forthcoming, claiming those characters as our own can be a symbolic gesture.
There are well-written characters explicitly on the spectrum, developed by both autistic and non-autistic creators. But the neurodiversity community isn't a little walled garden off to one side of the rest of society - we're part of the mainstream world as well, whether or not the mainstream realises it or likes it. Some of us pass, some of us don't. Some of us are diagnosed, many of us aren't.
And the characters we love and identify with are the same.
A few of my personal Aspie headcanon, i.e. the ones I can think of off the top of my head:
Sherlock Holmes, in most of his many versions. Mycroft too.
Hermione Granger, although I haven't read/watched Harry Potter in years and may be misremembering
Linda from Press Gang (now there's a blast from the past!)
There's a case to be made for Jeeves, but his skill at interpersonal prediction gives him a no vote from me.
What are yours?