Is this allowed?

[Mogwaii]

Got a question.

Can I write an age that happens to once have been inhabited by a person who also wrote himself into that age?
Here's where it gets worse: He isn't D'ni. I don't play off that much, it's just that he isn't from any known world. You do not meet him.
I'm guessing no, I can't.
But I wonder; because he is from an unrelated world, is that then okay? The chances of linking to a world someone else also had aren't really that slim are they? If the Rivenese just happened to be humans, if the people of Serenia are humans (or at least human like), and if Earth itself is inhabited by humans (just ones that don't live as long); is that really so different?
Yet then, the other way to look at it is that because he isn't D'ni, I just made up out of nowhere that there must be another "great tree", one that has now connected to the one of the D'ni.

[Whilyam]

This is interesting. Since you're not dealing with anything relating to D'ni canon, I'd say it's okay. The potential for this sort of character would be interesting.
We know that all sorts of weird things can happen with the Art (Notable for this case, Atrus finding Branch, Emmit, and Will on Stoneship). Personally, I like that sort of thing.

[Calam]

I think this is an interesting idea. I toyed with a similar story a while back. I don't see how it violates canon in any way.

[Jadawin12]

Seems pretty reasonable to me... more reasonable than some of my ideas in fact. My input, go for it.

[Egon]

It's ok as long as 1-2 people will came with such idea.
If everyone will try to do the same thing, now that would be canon breaker.

The chances of linking to a world someone else also had aren't really that slim are they?

If You talk only about D'ni, then yes they are. Chances of writing description book by someone else to the _exactly_ same Age are very slim. It might be very similar looking Age, but usually it's different. In fact before Yesha magic there wasn't such case in entire D'ni history (as far as I know).

Now since You talking about different then D'ni race, which might have a little different Writing and hence a little different Writing rules, that saves this idea.
But again, we should keep away from spawning lots of different Great Tree, cause that probably breaks canon.

If the Rivenese just happened to be humans, if the people of Serenia are humans (or at least human like), and if Earth itself is inhabited by humans (just ones that don't live as long); is that really so different?

No. Rivenese just happens to be Rivenese, and Serenias just happens to be Serenias. And D'ni are D'ni. Now You might say, that all those species are very similar, but can't say they all are humans.

[kaelisebonrai]

actually, one can generally /assume/ that all of them are at least of the species: "Homo sapiens" due to the fact that a human can breed with a D'ni, and produce offspring that is can breed with Keta's people, (iirc, humans? not sure), who's offspring can breed with the Rivenese.

Or, quoting XKCD - "Science! It works, bitches!"

EDIT: note, I'm /not/ saying they're all "Homo sapiens sapiens" though. =)

[BAD]

Since the great tree of possibility has every possible outcome for branches it's entirely possible a creature could learn to create links without full or any knowledge of the D'ni. *Cough* Bahro *Cough*.

So if you make your character have a way to create links that doesn't necessarily use the D'ni writing system, or is very similar, than it may be possible they would eventually cross paths with the D'ni who also write links and explorer ages. So at that point perhaps he or she did find themselves in an age that a D'ni had created a link to.

Completely plausible and sounds interesting.

[Mogwaii]

alright, cuz i actually was wanting his writing to work a little bit differently.
and just wondering, could you write a link to an version of earth that is THE version of earth. the one Cyan lives on?

[Mogwaii]

this is kinda interesting because by doing this now i can make up whatever i want about writing because it doesn't interfere with the d'ni.
it almost seems wrong to go that far though.

[BAD]

alright, cuz i actually was wanting his writing to work a little bit differently.
and just wondering, could you write a link to an version of earth that is THE version of earth. the one Cyan lives on?

The probability of that is astronomical. Almost infinity to 1 and probably so. You want to avoid making a god like character as in fan fiction, this tends to either bore or annoy those who read it. If your character can write links to specific places using intuition or he is just so lucky that he writes exact links to important places within the existing storylines, than you risk making them seem too powerful and that's when people get upset. There are more plausible ways for your character to end up on Earth if he has already come across D'ni worlds. A hidden D'ni linking book for example in the age he and the D'ni mutually wrote about.

However, it's your storyline and if you're not worried about gaining any kind of acceptance, then go for it. I'm waiting for some Uru Marysues too. I can't wait for someone to write a story where they are Yeesha's best friend and Yeesha asks them for advice or to write books for her.