There have been similar sounding stories written to what you've described, it would just be a matter of finding something that would make it unique from the others. but is would be good, as vl_redreign suggest to check out getithere.
And actually, if you find one that is abandoned that might be worth continuing, there's a new comm on LJ adopt_a_wip http://adopt-a-wip.livejournal.com/ where the author is contacted to see if she or he is willing to have their fic completed by another willing author. you should check it out for more info.
and...now...I was just reminded that this weeks Drabylon prompt (livejournal as well) is a Justin & Ethan pic. so if you have a hundred word idea fic, you could write it and post it there :) drabylon.livejournal.com/