Chapter two:
Papyrus leaps to his feet and fires a bone attack at the monster. He manages to hit one of the tentacles but it does such little damage that only the tip is destroyed.
The monster attacks Papyrus with the tentacles just like it did to Undyne and Papyrus is struck knocking him to ground.
"Papyrus!" Undyne gasps.
"I'm okay." Papyrus tries to assure her while holding back to pain in his voice.
"I d-don't think we're going to get anywhere with this." Alphys admits.
They look at the monster ready to defend each other, though Alphys remains in Undynes arms, even if they are losing badly.
Suddenly a bone flies out of nowhere and slams into the floor making the monster have to jump back to avoid it.
"Wow Papyrus. That was your best attack I've ever seen." Undyne says impressed.
"Um that wasn't me." Papyrus admits.
"Then who-" Undyne is however interrupted.
"GASTER!" Sans shouts in anger and everyone turns to where it's coming from. He's standing on the edge of the end of a hall that seems to drop down into the room as he glares down at the monster. He jumps down landing in front of the other three and he's still glaring at Gaster.
"Sans!" Papyrus happily calls the others name glad to see the other.
The monster, Gaster, turns and swipes a tentacle behind himself. He activates a computer with a white sound wave on a green screen.
"Opponent scanned. Ready." An electronic voice says and Gaster turns back to Sans only to say something.
"5A-N5?" Alphys questions. "I-I think you mean Sans?"
One of Sans's eyes glow blue and have a slightly transparent trail coming from it. He throws one hand forward with the other in his pocket and a bunch of bones go towards Gaster.
Gaster moves doing his best to dodge but gets hit a few times gaining more damage than from Papyrus.
Sans sends bones out a wave of bones coming from the floor and Gaster moves to the side but the parts the slowest at dodging get hit and destroyed.
"Oh." Alphys says in realization. "I get it. The only magic that can damage it is the kind of magic t-that Papyrus and Sans use. Skeleton magic!"
"That means that we can do this." Papyrus turns but suddenly some blue bones come up in front of the three as if Sans is keeping Papyrus from joining. "Sans!" He complains but Sans focuses on fighting Gaster.
Gaster keeps trying to dodge but Sans's attacks move rather fast and in rather well thought out patterns making it difficult to not get hurt. He sends out some tentacles but Sans sends out a bunch of bones that destroy the tentacles before they can reach him.
Sans then sends out some bones with a wave like gap that Gaster jumps through though parts of him still touch the bones taking damage.
Gaster lands and sends out another tentacle attack but Sans grabs them in his gravity magic throwing his hand up. He is released after all tentacles are destroyed from the bones that shoot down from the ceiling.
"Power at forty five percent." The computer says with the line moving as it speaks.
Sans sends out more bones at Gaster causing them to fly through the air like thrown knives making him back up and gain more damage as a few hit.
Gaster charges towards Sans and Sans moves his hand again for another attack.
This time Sans makes a wall of bones that shoot up from the floor hitting Gaster in the front pretty hard.
Gaster who has taken quite a bit of damage makes an almost growling like sound then he melts disappearing from sight.
Sans looks around on his guard trying to spot Gaster before he attacks.
Suddenly Gaster forms quickly behind Sans and Sans only has enough time to glance back before Gaster charges. He throws himself over Sans only to jump back with a screech as Sans shoots bones up around himself. He melts disappearing again letting the other three be able to see Sans between the gaps of the bones.
Sans seems to be at least a little injured and he is almost laying on the ground causing Papyrus to scream his name in fear and worry. He sits up then gets to his feet, making Papyrus feel some relief, as he quickly checks his HP he's at 0.5 HP. He looks out for Gaster as his bones from his attack disappear and he knows that he can't take much more damage.
Gaster forms in front of Sans who tries to fight but stumbles as he is feeling weak. He chuckles at the sight.
"Attack power at twenty five percent." The computer says. "HP reduced to point five."
"Sans!" Papyrus calls worriedly as he doesn't want his brother to die.
Sans closes his eyes and takes a deep breath. He knows what he must do. He lowers his hand moving so he stands there with his hands at his sides. His eye stopped glowing for now.
Gaster is about to charge again when suddenly the computer speaks.
"Overload in progress."
Gaster turns in shock to the computer with a surprised noise.
"W-What?" Alphys questions.
"Self-awareness protocols disengaged." The computer continues as Sans's head drops almost as if he fell asleep. "All systems reaching critical levels."
Sans's Gaster blasters appear on either side of him ready to fight.
Gaster spins to look to Sans obviously in shock.
"Meltdown in three... Two... One..." The computer says with a slightly quick count down.
Sans's eyes snap open at this.
"Disengaged?" Papyrus asks then suddenly Sans throws both hands forward.
A bunch of bones go right for Gaster starting from the ground then as Gaster jumps the Gaster blasters Sans has out fires a beam hitting Gater himself. This knocks Gaster into even more bones that slam out of the wall like the wall isn't even there as all everyone of magic attacks usually do.
"I-I've only heard stories of this kind of thing happening." Alphys admits. "B-But only because of how dangerous it is and not just any monster can do it. P-Perhaps the can easily sleep anywhere part of him helped in being able to do this."
"Do what?" Papyrus asks as he and Undyne turn to Alphys.
"Um well what the computer said." Alphys glances to the fight that now looks like a mess of bones coming from every angle, Gaster blasters beams coming from Sans and Gaster himself trying to dodge but taking so many hits... Though the computer has been torn to pieces by now with the pieces being turned into smaller pieces all thanks to the escalated fight. "Self awareness protocols disengaged. I-It's computer speak for that he, Sans, let himself go mentally unconscious. Like h-he isn't really aware like his body is controlled by something else without restraint." She explains turning back to the two. "This allowed his power to spike to really high levels and he's able to do more." She explains causing the two to blink in surprise. "I-I guess in some way it's like going unconscious to let your instincts take over for now... Um but he might get really tired quickly from u-using so much power at once. He's trying to destroy Gaster before he becomes tired and vulnerable. It's dangerous for both the monster doing it and whoever they are fighting. So it's highly not recommend even if it's rarer for a monster to be able to even do it in the first place, but it m-might be the only chance we have at stopping this Gaster guy."
They all turn to watch the fight as Gaster jumps back to dodge some bones shooting up from the ground; only to be struck in the back from bones that fly from behind him.
"Please be careful Sans." Papyrus pleads a little quietly in worry.