There's none of the panic or denial you might expect from such a realisation – just calm acceptance. Maybe even relief.
You're dying and that's okay.
Perversely, your last thought before the darkness claims you is Sans. Heh, he's going to be so mad. You've royally messed up his plans now, whatever they are... were. It's almost funny, imagining the lazy skeleton all pissed off. At least you have that warm image to accompany you to the grave.
The world has turned to shit in the forty years since Frisk and Toriel's untimely deaths. Monsters rule the surface in quiet despair, while human resistance factions - fueled by an unrelenting hatred - continue to prod at the festering wounds left by a war few really wanted.
Sans has a plan to fix it though. He'll have to flirt with the fine line between what's right and what's best, but if everything pans out the way he hopes...
The end will justify the means.
Unfortunately, he needs your help to pull it off, and you're far from being the most cooperative rebel he's ever met.
- Part 1 of Life Lessons
Sans has gone off the deep end. After years spent agonising over his loss, terrified you'll never exist in this new timeline, he finally cracks.
He'll make sure you come back.
Alternate ending to 'The Mathematics of Love and Loss'.
- Part 2 of Life Lessons
Undyne and Alphys handled their grief in very different ways.
Perhaps then, it's not so surprising that things ended up this way.
*Kind of a prequel to 'The Mathematics of Love and Loss'. A little insight, for those who were interested, into the sinking of Undyne and Alphys' ship.*
- Part 3 of Life Lessons