one argument you often see about fanfiction is that it's like 'training wheels' writing? like 'oh it's fine to do that while you're still learning, it's easier than coming up with your own ideas'. and I have to say I have just never agreed with that.
in my experience it's actually pretty common for newbie fanfiction writers to gravitate towards coming up with OCs rather than writing about the canon characters (hence the infamous Mary Sue); this suggests that many people find that 'easier' than attempting to write about pre-existing characters.
I would say that recreating the characterisation, mood and general vibes of an existing work of fiction is in fact a skill in and of itself that's acquired via practice. A common compliment delivered to fanfiction writers is how well they have captured the spirit of the original work. Inexperienced fanfiction writers fail to do this.
When creating an original character you can, ultimately, say anything about them and now it's canon bcos you created them and you said so. conversely, well, if you are covering a well known song and start playing the wrong notes people will notice immediately.
In addition: a lot of fanfiction, IMO, is in actuality a form of metafictional literary analysis. a story where two characters sit down and talk about their feelings about a canonical event? literary analysis, which is of course a skill. Sometimes fanfiction is bad bcos the writer is not good at interpreting texts.
finally I have made this point before but you never really see anyone suggesting that fictional works based on existing public domain texts are on 'easy mode'. is it 'easier' to write something based on a copyrighted work than a public domain work? Of course it isn't.
I know I said 'finally' but I forgot a point:
A major strength of the transformative work is its ability to create dramatic irony. If a fanfiction's emotional resonance is dependent on being familiar with the source material that's not necessarily a bad thing. sometimes it's a sign that the author has done a really skillful job of engaging with said source material.
Every writer needs to remember that writing is not a single "thing."
We're all putting words to paper, but as writers, you know perfectly well that a poem isn't flash fiction isn't a speech isn't a script isn't a novella isn't one in a series isn't a song isn't a textbook isn't an instruction manual isn't a commerical.
Just because you personally find it easy to write using the existing characters does not mean:
It's easy
You didn't have to develop a skill for it
You're any good at it
It just means it's what you've chosen to write that at that time.
You could be even better writing something that's 'objectively easier'. You could be more successful writing something you spent more time developing skills for. You could enjoy writing something you struggled with and would never share.
And someone else could think one or more of those applies to what you consider "easy."
And as for training wheels: you can learn to cook the most beautiful meal in the world, and that still wouldn't mean you know how to navigate someone else's kitchen. The only practice you get from writing fanfiction is writing fanfiction. You may recognize the same elements in a different form of writing, but the context changes entirely, and there are whole bunches of considerations to keep in mind that fanfiction doesn't have - and ones it does have that don't apply.
