So here's a good moment for me to sing one of my particular praises of fanfiction.
We hear a lot about why fanfiction is a starting point for writers, but the implication of that is that one will/should move on to original works, as if fanfiction were a genre of the immature storyteller. Not so. Fanfiction is an ode to the state of being in love--in this case, in love with a particular set of characters or fictional setting. For those who share that love, it can be compared to the composition of hymns in a religion. Those who share your religion get it, while those outside of it just think you are strange. But no one says, "Why don't you stop writing those hymns and write some real music?" They may despair over your choice of music genre, if they're not into that religion, but they acknowledge it as a legitimate form of composition.
But there's an aspect to fanfiction that can't even be sustained by an "in love" or "religion" analogy. Fanfiction can satisfy our creative greedy hungers to find out not just what will happen, but to see how we'd feel in the face of many possible outcomes. Fanfiction is a sort of quantum physics of the storytelling world, a kind of Rashomon hivemind where we never have to ask ourselves who had the definitive version. No other fiction is like this. I can read/write a story where Harry falls in love with Cho, then one where he falls in love with Lupin, then one where he saves the world from Voldemort and lives happily ever after, then one where he's killed in the process. And here's what's singular: none of these stories contradict each other. Because they are by definition fanfiction, and somehow, because fanfiction never earns the label "The real version," we can enjoy each of those stories--even the death fics--without feeling the "This is how it is, set in stone" finality that would accompany any other piece of fiction. It's unique. It's a live AND dead cat-in-a-box, and no one has to choose a moment to open that lid.