Dragons, Spike knows, live a long time. So much can happen during that time. And that scares him. So, what does he do? He seeks out advice from the wisest (and oldest) mare he knows - Princess Celestia - in the hopes that she can help him deal with his worry.
It's not quite what Celestia expects him to ask, but it's an important question nonetheless.

Written for the Smaugust prompt, "Celestial." This has a happy ending btw, the "Sad" tag is because, well, it makes Spike sad.