Crowd Control

Can you find a collaborator on the internet? There is no reason at all why long-distance collaboration should pose a problem with the many tools that we now have at our disposal.
Many of the same rules for finding a collaborator still apply. You should not leap into action and commit to a large piece of work without having a fair idea of what your partner is really like as a person. Bear in mind that what a person reveals of themselves on the internet might be a carefully honed persona. Not everyone is straightforward about who they really are. Respect people’s right to privacy, if they want to maintain it. You should also be circumspect about giving away too many personal details in a public arena. Let common sense prevail.
It’s a much larger pool of people to choose from, so how might you go about it?

Online writing groups.

There are online equivalents of writing groups, which have similar aims of mutual support and constructive criticism. Look around to find one that aligns with your interests, and spend some time seeing how the members interact with each other. If it seems like a place that engages you then join in, and keep your eyes open for other writers that you think you could work with. If it’s the kind of group that has forums or chat, then you can mention that it’s an interest of yours and see who comments, but it should not be your only reason for visiting the site. Take part in the core activities as well, and try to get to know the other people.
I firmly believe that finding a collaborator, while it might remain your main goal, should become a secondary activity to getting to know other writers, however you seek them out.

Favourite author websites.

Some authors have elaborate websites where fans can hang out with each other and discuss their work. If one of your favourite authors happens to have one of these, then it’s an obvious hunting-ground for potential collaborators. You must remember that not everybody there will be a writer, they are primarily there because they are readers. A surprising number will be writers though, and you already know that they enjoy similar fiction. This can be a great short cut to sharing worlds, sharing styles and sharing background knowledge. You’ll hopefully be striking out and writing something unique, but having a common reference, vocabulary and mindset can make that easier.

Fan fiction.

If you like the idea of finding other writers who enjoy the same things as you then do consider looking at fan fiction. There are many people who enjoy their favourite fictional worlds and characters so much that they write their own stories to fill in the blanks, or put the same characters into different situations. You won’t be able to sell fan fiction, it’s written for pure enjoyment, but you will find like-minded writers. It is very straightforward to track it down. Websites such as https://www.fanfiction.net/  have it organised into intuitive categories so you can find what you’re looking for very quickly. There are discussion forums too, for people to discuss their common passions. If you are planning to write genre fiction and want someone who shares your taste, then why not take a look here, where you can instantly drill down to exactly those people?