Not having read this 'Spencer Quinn Fantastic Fiction', it's difficult to name the main characters. However, in Spencer Quinn's general body of work, he often creates characters that are relatable and complex. There might be a protagonist who is intelligent and observant, perhaps a sidekick who provides comic relief. Or there could be a character who is the antagonist, causing trouble and obstacles for the other characters. It really depends on the specific stories within this 'Fantastic Fiction'.
I don't know for sure as I'm not familiar with this specific 'Spencer Quinn Fantastic Fiction'. It could have characters like a detective or an ordinary person caught up in extraordinary circumstances.
Since we don't have much information about this 'Spencer Quinn Fantastic Fiction', it's hard to say exactly who the main characters are. But in Spencer Quinn's works, there are often characters with distinct personalities. Maybe there are characters who are on a journey of self - discovery, or characters who are trying to solve a mystery or face a big challenge.