I've also been gripped by an idea for a fanfic, which further saps my desire to work on the story. Why is it so (relatively) easy for me to write fanfic, and so difficult to make the jump to fully original works? Am I going to be a fanfic writer the rest of my life, with a mere handful of fans and no money? Well, of course there's no guarantee of money even if I do manage the switch to original fiction, but still.
The good news is that I have finished translating the book and have started on volume four of the series. At least that's one thing I can look back on and say I've done.