Few years back I was reading an article on neuroscience discussing the idea of immortality becoming a very real possibility for humanity, somewhere within a hundred years time. Already we're close to understanding and slowing down, if not outright stopping, the aging process. And damage beyond that we can tackle by replacing failing organs with new ones grown from your very own cells. I know this is a little science-y for this subreddit, but the point of the article was that while a lot of the body could potentially be swapped in and out freely, the human brain was going to be a lot more complicated issue.

The human brain has an elasticity to it that inevitably decreases as we age, where it becomes more and more difficult for new pathways relating to skills and memories to be created. I know it's not entirely that simple but this is what it basically boils down to: We have a cap on our learning and potentially even our memories, and because there are no 200 year old human beings out there, we don't really know what will happen to a person when they hit the very end of that thread. Will your brain start overwriting old information, somehow, in a never before scene mechanism? Or will we simply spiral into madness as we lose our grip on reality, all because we can't store the information our overburdened brains are receiving?

I took this concept and applied it to my own writing. In a story I'm working on, two immortal characters sit down and have a conversation together. One the protagonist, the other a minor antagonist. The means by which they have become immortal is completely different. The antagonist is in a fountain of youth kind of situation while the protagonist is dealing with a kind of genetic anomaly. The antagonist is many thousands of years old, and his personality and sense of being are constantly being overwritten as the centuries pass and he forgets the events that defined his character. The protagonist is relatively young, verging just on a hundred years, but already he is starting to forget once vivid memories.

Anyways, the scene is rather nifty and I think it's a take on the immortality conundrum that isn't often seen in fantasy. Elves may designed differently to better cope with something like this, but I felt, for humans at least, having a tangible price they paid for the immortality outside the cliche "Everyone I know dies!" thing sounded like a good idea to me.