has this been done before, would you read it (short)?

Its an interesting idea certainly but it depends entirely on how it is written. A good idea badly written won't go anywhere and good writing cannot always save a bad idea BUT good writing can lift a weaker idea. So basically start writing and get some feedback. Good luck

I think it's interesting to combine and contrast the two people's plights: One immortal and doesn't want to be; one anticipating an early death and wishing it otherwise.

There is philosophy in it. It should also be dramatic, and a combination of characters and plot must DRIVE the story forwards. This could be a great story. But to be great it must be original - bear that in mind the whole time you work on it.

You state that the schoolgirl feels she recognises the new boy from "many years ago". If she's a schoolgirl now then how many years ago can it possibly be? Surely not VERY many?

The school context implies that the boy appears to be of school age. And he's ageless. So if the girl has seen him before he'll look much the same now as then. You will need to know why she feels she recognises him. It can't remain simply a feeling in the story - there must be a good reason for it. And if she has seen him before then that event must be known to you and a justifiable part of the story or story background.

There should be a good story-based reason why these people meet, and something compelling that keeps them together throughout the story. Also: How might she help him? How might he help her? Is there a common answer, even? Maybe something of his knowledge from the years past can help her? As the writer, you have many interesting things to consider! Be original.

Remember that if he doesn't age, he couldn't remain in anyone place for very long because people would notice he doesn't look older as the years go by. He's probably had to move on countless times. Maybe that's partly why he's fed up of life? Could that change? So many possibilities!

The presence of a "crystal" suggests a fantasy/magical story, as opposed to a science fiction story. Is that what you want? You need to know what your genre is in order to pitch your story to the right people in due course. Consider if a "crystal" is a cliche. Haven't we seen lots of crystals in lots of stories? So many crystals! Maybe there's something ORIGINAL you can create to account for the immortality?

To make your male character believable as immortal you must be very aware that he has lived for thousands of years already. And this must show in the story. The majority of his life experience has involved places, people, and events VERY different from the current time. Also, in all that time, he's likely to have learned very much about many things compared with the typical schoolboy of now. For example, he's had so much more time to learn about relationships, and many other subjects. So in some ways he's likely to seem "better", advanced, different! Unlike most schoolboys, he might (for example) be expert at archery and know how to tackle a boar bare-handed. BUT surely, he's also flawed! And perhaps the first big question is: Why is he unhappy at being immortal? The answer must show in his characterisation.

Remember, your characters will need obstacles to provide drama to the story. What gets in their way? Perhaps there is someone who interferes?

It's important for your story that it is distinct from other stories. Remember drama and plot. Don't be predictable. At least one (logical) surprise would be good. Be original. This could be a really great story!

Good luck.

So would the journey consist of her trying to find a cure to her health and the possibility that she knows this ageless man ? Make sure you add alot of character to the individuals, maybe deliberately be vague about the man. I must admit i like the idea but just try and some more depth (I know this a concept). For example, I would make him her lover from another lifetime and that's why she recognises him or even a guardian angel. She could have flashbacks or repressed memories.

Hm, it actually seems quite interesting, even though I'm over anything immortal since Twilight came out.

This could be a great plot - add plot twists and turns!

As you've got a moral to this story, remember to add a LOT of depth to the character - step inside her mind (and shoes), develop her quirks and flaws. You might end up with a martyr-like Mary Sue, as the girl is already dying, so character developement is CRUCIAL!

Hope this helped :D