Writing in known universes

[AwkwardlySet]

I’m a long time BattleTech fan,

RoboTech > BattleTech. Just sayin.

 

[Bramblethorn]

Then the issue isn't really the aging up, it's the copyright.

I think it's a mix of several things.

Pre-existing material like Disney, HP and Simpsons already has a fandom, and a significant chunk of that fandom is under-age. Writing fic in those settings can be construed as an attempt to court those under-aged fans.

Rowling has expressed concerns specifically about under-age fans searching for HP content and stumbling into porn, and implied that she'd take legal action to discourage this possibility. Disney would be much the same. So yes, that part's about copyright.

But also, when it comes to fanfic, aging up can be used as a nudge-nudge-wink-wink way to appeal to readers who want under-age: take a character who's canonically 16 or whatever, and mention that they're now 18 but without changing anything else about them. It's the same kind of thing as original-setting stories which open with "all characters are over 18" and then present a character who looks and acts several years younger. I could understand deciding that it's simpler just to ban aging-up rather than trying to define exactly which stories are doing this vs. which are legit.

 

[ElectricBlue]

Then the issue isn't really the aging up, it's the copyright.

I think it's both. The "true" HP canon relies on teenage characters, "aging up" is merely a way of getting around that - and as Bramble notes, it's the same bullshit as age disclaimers on stories.

Then, obviously, the copyright issues. I reckon Laurel has just said, Rowling, Disney, etc, too hard. Other fan-fic, not such a worry, just don't age them up.