Papyrus was surprised by Frisk's sudden hug. The human had seemed to suddenly pop out of the woods nearby him and hurl themselves into him, knocking him over in the process.
"ALLRIGHT, ALLRIGHT, HUMAN, IT IS NICE TO SEE YOU TOO! BUT IT'S ONLY BEEN A FEW HOURS SINCE WE LAST TALKED! BOY, YOU SURE DO SUFFER FROM A LOT OF SEPERATION ANXIETY!"
At Papyrus' claiming that Frisk had seen him only a few hours before, Frisk didn't know whether to laugh or cry. Sans just slowly walked up to his brother, his smile bigger than it had ever been, and his eyes watering. Frisk let go of Papyrus, not before planting a kiss on his forehead, and then leapt backward, rushing off without Sans to find Asgore and Toriel.
Sans just kind of staggered toward Papyrus, in an almost dreamlike state, as if there were no thoughts in his head whatsoever. Papyrus noticed his strange appearance.
"ARE YOU ALLRIGHT, SANS? SANS, WHAT'S WRONG?!"
The shorter skeleton gulped and wiped away a tear.
"nothin's wrong bro. nothing is wrong. nothing. i'm not just allright, pap. i'm better than i've ever been."
Sans suddenly rushed forward at blinding speed, burying his head in Papyrus' chest and wrapping his arms around his back.
"it's so good to see you, bro. it was real bonely without you."
Papyrus hugged Sans back, and lifted him into the air as he replied.
"STILL YOUR SAME OLD SELF. I MAY NOT BE SMART ENOUGH TO FIGURE OUT WHAT FRISK AND YOU DID, BUT I THINK I'M SMART ENOUGH TO KNOW WHEN YOU HAVEN'T SEEN ME IN SOME TIME, AND I KNOW THE AGONY THAT CAN BRING UPON PEOPLE."
"i love you, bro."
"… I LOVE YOU TOO, SANS."
Meanwhile, Frisk had ambushed Asgore with a very surprising hug, and Toriel with one that was more of a pleasant surprise. Toriel didn't quite pick up on the fact that something was wrong with Frisk, but Asgore had only been hugged by the child once before, and that was… wait, when was it? Asgore didn't actually remember a time that that had happened. Strange, it just came naturally to him that that had happened once before. But he couldn't remember a time when it had actually happened. Whatever. He was getting old.
Meanwhile, Frisk was literally prancing about the Underground, and eventually out of it, gripping anyone they saw in a crushing embrace. They were so glad to be back home that they couldn't even see straight.
For the last several years, they had been trapped in an alternate universe, and while they could have hardly picked someone better than Sans to be trapped with them, everything was always so strange. No matter what, there was always something wrong with the timelines. Either an alternate version of them had been causing trouble, or their friends had their personalities swapped, or everyone but Flowey was evil, or something of that nature.
But here, everything was… right. Everyone was exactly who they were supposed to be. Papyrus was an over-the-top, constantly optimistic skeleton who couldn't fight to save his life (but could to save his brother's, apparently), Toriel was a loving, caring, motherly goat woman, Asgore was a towering, slightly inept, caring old goat man, Alphys was a nerd and weeaboo who it was impossible not to love, and Undyne was an endearingly angry fish woman who also found it impossible not to love Alphys.
And the relief Frisk felt upon seeing them all once again was overwhelming. After Frisk had greeted literally every single monster in the underground, they began searching for Asriel. Er, Flowey. It didn't matter. Frisk had been to more than one timeline in which Asriel was safe and sound and not Flowey. They just knew that they would be able to SAVE him.
So they went looking. And about an hour later, they found him.
But they didn't really appreciate the circumstances. Peeking into a rather well-hidden area near the Barrier, Frisk caught sight of Asriel playing with his best friend… Chara. The Fallen Child had uprooted Flowey and was holding him in the air.
"H-hey, l-let's talk about this, ok? R-really! We could, we could work together! We could conquer the whole world! P-please, no! It's me, Chara. Don't you remember me?"
Tiny white tears were seeping from Flowey's terrified eyes, and his face morphed to resemble that of the child he once was, Asriel Dreemur. But Chara didn't even hesitate. They had, to be fair, stopped killing Flowey in their own timeline, but that was just because the weed had proven useful on more than one occasion.
"Please! Please, show some MERCY! Chara, don't you remember me? Please! Somebody help! Somebody SAVE me!"
Chara leaned in close to Flowey's face and grinned even wider.
"But nobody came."
Flowey almost died of a heart attack right then and there.
"Sorry, Chara. I came. And I have no intention of letting you kill Asriel."
"F-frisk? Oh, thank god! I-i… help me. Please, please, help me."
Frisk smiled themselves and hefted their knife, so useful for cutting vines. Chara raised theirs and laughed out loud at Frisk.
"You honestly think that you can kill me? After what I did to you before that RESET? Papyrus caught me off-guard. I won't let it happen again."
"Does this catch you off guard?"
Frisk dashed forward at Chara, swinging their knife, and Chara parried, expecting Frisk's arm to move in a predicable pattern, like it always did. Chara had years of fighting experience, and Frisk always spared their opponents. Here, Chara had the advantage, even if DETERMINATION made Frisk a bit physically stronger and more durable.
But they were wrong. Frisk, instead of losing their grip on their knife as Chara had expected, skillfully twisted the blade, almost making Chara drop their own weapon. Frisk instantly followed through, bringing the knife down on Chara, who was barely able to block the strike.
"How are you…"
Frisk continued a brutal combo of attacks, each strike making the knife's telltale sound. Chara was surprised by Frisk's ferocity.
"I don't understand…"
Frisk kicked Chara in the chest, sliding them backwards, before charging in with another blow, which Chara narrowly slipped away from.
"Why are you…"
"So good? So strong? So ferocious? Guess."
Chara hurled their entire upper body backwards in what was almost a limbo position, dodging a wild strike from Frisk.
"I want to you guess why I'm winning."
Chara slashed repeatedly, again and again and again, but Frisk easily parried each attack and followed up with one of their own, one that was less easily dodged. Chara, once again, began fearing for their life.
Chara was filled with DETERMINATION.
And Chara began fighting back. Each slash was harder, faster, and more precise than the one that preceded it, and Frisk had more and more trouble blocking them.
For a moment, suddenly, the battle paused. Both had their knives raised at arm level, and both prepared to bring the weapons down on the other. Frisk and Chara both attacked with all of their strength, and the impact of their blades actually cracked nearby stone. The two humans both failed to keep their grip on their weapons, and each knife flew out of their hands. A moment before they scrambled to grab them, they were both sidelined.
Flowey looked positively awestruck. The two followed his blank stare upward, to the top of a nearby boulder. Both of them gasped, as they practically felt the DETERMINATION drip out of their bodies.
"You're not Chara, you little punk. Hold still, Asriel. This'll only take a second. Oh, and Frisk? Nice moves."
They jumped from the top of the boulder.
Twilight was shining through the hole where the Barrier once was.
They were filled with DETERMINATION.