Another day, another reset. SANS was getting tired of it. Some timelines were ok where not every one dies, but the outcome of the humans interactions didn't cause too much irreparable damage. Except removing the nice lady of the ruins. That was the last one he came out of. No response to his knocks. He knew she had to have been killed. And it pissed him off. Trying to live in a world of anarchy, that's just fun.
He was just getting used to everything too when he restarted. Right after the promise of watching over whatever creature, human or a creature calling itself a human, the walks thru those doors he's guarded for years. When Papyrus came along to scold him for not setting up puzzles to trip up any humans. Sans had a migraine and did not feel up to the usual antics of his brother.
"look Papyrus, I don't really care about puzzles today. I have a skull splitting headache right now."
"AH, BUT DEAR BROTHER, IT CAN BE ANY DAY THAT A HUMAN COME BY HERE, AND IF I CAPTURE IT I WILL MOST DEFINITELY GET ON THE ROYAL GUARD!"
Sans was tired of hearing this spiel; one he's heard countless times. "BRO! Puzzles ain't the way to capture any stupid humans, and puzzle ain't the way Undyne or As gore will let you on the guard. It's a pointless endeavor and you should grow up and think of smarter ways to capture a human!"
The moment the words were out of his mouth, he regretted them. The look of hurt on his brothers face hurt worse than any time the human killed him. Unscheduled tears hovered at the edges of Papyrus's eye sockets.
"Um..." Papyrus's voice caught. Clearing his throat he tried again, "THAT MAY BE YOUR OPINION BROTHER, BROTHER, BUT PERHAPS WE SHALL LET THEM DECIDE?" Papyrus turned heel and ran off, a small 'nyoo hoo hoo' on the wind.
Sans felt like a heel and fell back against the side of his post. He didn't mean to say it. Pap has always been sensitive about his puzzle obsession, practically his whole life. He scrubbed a hand over his face, hoping the scraping sensation would clear his mind. He would give Pap a chance to calm down, then he'd find a way to make it up.
Too bad this timeline never would allow for it. The next time he saw his brother he was a pile of dust. His heart broken over the loss, and the fact that for the first time he couldn't with for a reset, urged Sans to vow to always make sure that whenever possible to cement encouragement for his brother's aspirations. And to make sure no one, not even himself, would ever hurt Papyrus like that again.