This question is clearly written from a fanfic perspective so I will answer it as best as I can: yes, from a narrative standpoint I have to (and they die of age eventually), but I tend to get overly attached to dead characters and try to find excuses to resurrect them and it's a damn good thing I write fantasy for that, but seriously it's a bad habit I ought to break. I have a hard time leaving people dead.

In fanfiction I'm always grateful when people warn me away from it because I'm almost never in the mood to read it.