I write funny, opinion based articles. I haven't come across too many people who do this, but then again, I haven't been looking!
The majority of the articles I find on here, are the ones that are geared towards pulling in people, and trying to make money. It's people writing, "How to", articles and "news report", style hubs. There are quite a few people who don't seem to care what they write, as long as they write a lot of it.
I came across two different girls who wrote complaint articles last night. One complained about her husband never using the hamper for his socks. And the other wrote about how hard it is to find a job, strait out of college.
So the answer is "yes", you can write fiction.
I'd suggest that you write what you know the most about. Or simply write about whatever you want, within the hubpages parameters. Some people on here, write nothing but poetry. Some are all about tips, or reviews. I don't try to use other people's hubs as the standard by which I write mine. I rather be original, than just another face in the crowd.
I just thought up a new idea for how to write some interesting hubs. I won't share it, but it's a little goofy. It will involve me writing some non fictional stories. I asked a few of my followers what they thought of the idea, and they all liked it!
So if I can write the goofy things I write, and people care to read them, I'm certain you can write the way you want to as well. If in doubt... Run some of your ideas past your fans, and see what they think!