Well, I view fan fiction as something of a cult unto itself and feel that it has its own place on the internet, as do the historical forums and the forums for discussion of the movie. I know that there is crossover - some writers of Alexander fan fiction research quite extensively and have participated on Pothos. It follows that new readers of these stories may well find themselves doing the same.
I think that in normal circumstances it is usually those already familiar with fan-fiction who will seek out the tales and/or become active within that particular online community. So if someone looking for historical information on the Web accidentally comes across a story and finds it frivolous, their most likely response will be to ignore it. OTH, if they find a story interesting (as you did) then they may look for more.
As for the nature of some of these stories which you so gently tried to describe; I certainly don't feel that they do any harm. But then again, I felt the same way about the movie (which I didn't hate) while others have strong feelings that it did a disservice to Alexander. My thoughts are that it is only a movie - one that has come and gone - and although there will still be a few who will discover it for the first time on DVD, it definitely hasn't changed the way historians study Alexander. And there is no reason that a fictional film ever would! I appreciate that those who liked the film are more likely to pursue an interest in the historical Alexander, and some here may argue that a better film, in their opinion, would have encouraged more study, but I am not sure if that is true or not. One thing is for certain: I have watched the fan-fiction community flourish since the movie. I don't participate and I have only read an occasional story, but a search of Yahoo, for example, will show disproportionately
huge numbers of people (when compared with the historical Alexander forums) who have joined fan-fiction forums focusing on characters from the film. If only a few of them transfer their interest to the historical Alexander, it will still be a good thing.
Are you aware that Jeanne Reames-Zimmerman has written an article which discusses in part internet culture and fanfic, both before and in the wake of Oliver Stone's Alexander? The article will be published in a Lane Fox/Greenland anthology of responses to the movie. A little more information on this can be found
here. No news yet on a publication date.
Best regards,