It is known that no magic is forever; if the Spell of Immortality (initially cast by Cosmic Crown the First over all of Equestria) is reversed, everypony's physical form will decay. From this point, there is no return, and the Cycle of Life will resume.
There was no question: it was better to live. Then why did it feel so empty, living here forever? Twilight was faced with a difficult decision; once made, it would affect not just her, but everypony she knew and had come to care for. Was it truly better to live in ignorance, or was that just an empty solution? Knowledge is power and truth is empowering. Did that make everypony alive not only ignorant, but weak--too weak to face the truth?
Either way, Twilight had a decision to make. The indecision and lack of knowledge only made her that much more determined to find a solution. And so she trekked on.
If she doesn't know what death and decay are, does that mean that all other plants and animals are also immortal? Or that there aren't any? Also, I have yet to see a real motivation emerge to undo the immortality spell.
Nevertheless, this is interesting.
4565316
Yes, that would imply that all living things are immortal. :)
That is true, there is no real motivation to undo the immortality spell, but she is motivated to learn all she can about the situation as (in the fanfic) she has never experienced true happiness and she feels this immortality spell has something to do with it. I tend to write as I go, so there may be plot holes that I'll have to work out. In the meantime, thank you for responding and I hope you enjoy/continue to read updates! :)
4566359 That leaves me with more questions about the nature of this immortality. Does it just mean nothing dies of old age? If nothing died, period, but there was still reproduction, the planet would be covered in microorganisms to a considerable depth. If, on the other hand, there was no reproduction, why would Twilight not know what death is and why was the spell cast by Cosmic Crown "the First"? If there was reproduction and no age-death, but things could still get eaten or whatever, why would Twilight be ignorant of death? Do organisms still have to eat? What do they eat?
4566687
All very good questions. Perhaps they don't truly "die" at the time being, but instead they end up traveling to new dimensions when it would be considered "their time". Also yes, I imagine they still eat and drink, but more because nature dictates it to be so (muscle memory, so to speak). Their immortality is against nature, which is what causes Twilight's discomfort.
I wonder if the universe even works the same way ours does. There is grass and plants, other animals. Perhaps death exists, but it is some sort of secret that nobody talks about. Or maybe only the ponies are immortal. I'll have to decide on a spin to this, you've brought up some very integral questions/possible plot holes I've overlooked. Thank you. If you wish to continue bouncing ideas off me, you can PM me. It might be really helpful if you want to assist in developing the story. You'll be credited of course. ^^
Could you put a Flashlight romance in your story?