I'm so sorry for mistakes or weird phrasings, I thought of this and got excited, so I wrote it in line an hour and a half! Hope you enjoy! ;)
The pitiful remains of Asriel's petaled husk lay motionless on the ground.
...That was it. That was the final monster needed to achieve this new ending, the ending of no mercy and no remorse. They would've thanked Asriel if they could, but, alas, he was dead, just like everyone else.
Frisk looked on from the remains of the last monster, only to see an entirely new one. What was in front of them was not a human, no. It had ominous red eyes with a permanent glazed smile. It was the demon who came when they called its name.
"Greetings. I am Chara."
Frisk stood their ground as Chara approached, her crazed grin only growing. She gave a low chuckle. "Thank you," she said. "Your power awakened me from death. My 'human soul'... My 'determination'... They were not mine, but yours."
She began to maneuver around Frisk like a cunning cat, probably as some childish intimidation tactic, but Frisk stayed still all the same.
"At first, I was so confused. Our plan failed, hadn't it?" Chara continued, briefly glancing to Asriel's pathetic plant parts. Her eyes showed no remorse, much like Frisk's in their own slaughtering.
"...Why was I brought back to life?" she lamented.
Chara's head snapped towards Frisk, her smile still eerily prominent.
"You," she revealed. "With your guidance, I realized the purpose of my reincarnation… Power."
Chara snaked around Frisk, eventually returning to her original spot. There, she continued her spiel, "Together, we eradicated the enemy and became strong. HP. ATK. DEF. GOLD. EXP. LV. Every time a number increases, that feeling… That's me."
Chara gave another dark chuckle, opening her mouth to extend a hand, an offer, to her lovely partner, but she was cut off by a mysterious noise.
A ringing. The ringing… of a phone.
Chara's ever present smile faded as she glared daggers at Frisk. "Why did you keep that… that thing?" she asked, crossing her arms.
Better yet, Frisk thought, why was 'that thing' ringing? They killed everyone. Everyone was dead. No one should be able to call them.
Frisk intended to let the phone go to voicemail, but it just kept ringing. Ringing, and ringing, and ringing… It was endless, strange, and frankly quite annoying.
"It would be impolite not to answer," Chara pressed, curious herself as to what exactly was going on. Though, her face stayed as stoic as Frisk's as she watched the fallen child hesitantly grab the phone out of their pocket and accept the call. She moved closer to hear the other end.
"Hello? Is anybody there?" said a strange, distorted voice. Neither of the determined beings in the room recognized it. Typically, Sans said this dialogue after Frisk completed an non-pacifist ending. But it couldn't be him… Frisk heartlessly slaughtered him just moments ago.
The voice gave an emotionless chuckle. "Well, it appears I will just have to leave a message…"
There was a small pause, static background noise overtaking the call as the mysterious voice thought. Moments later, it started to speak once more,
"Never did I think I would exist to see this day. Monstrous children of man killing monsters... In my days of… corporeality, I did not believe that humanity was evil. It would surely be unfair to judge the humans as they did us. Wouldn't that make us just as horrible as them? Now, though, I believe that perhaps I should retract my former beliefs.
"Everyone in the Underground is dead, courtesy of the two emotionless vessels I am now speaking with." The voice was harsh, dripping with surprisingly bridled fury. "There is no one left to lead, no citizens left to guide. Not even a single dog to sleep on the throne. And for what purpose? A sense of fulfillment? A new ending? An aching yearning for power?"
It scoffed.
"Actions like these are not justifiable. I see no excuses. You have wrecked my former home, hurt countless, countless people… And you will not stop here, will you? Yes, what you are searching for can never be satiated…"
Strangely, the voice took on a new surprisingly kind tone. "If you don't mind, I do believe I will came around for a visit. Too long have I stayed in this motionless void." However, that nurturing sound did not last long, as after that sweet phrase, the voice spat at the two,
"Today, humans, I will avenge my sons, and my people.
"You are not above consequences."
A deafening static quickly replaced the daunting voice on the other end of the line. Frisk stared at the phone. For the first time along this path, they began to feel... apprehensive, like this wasn't right.
Chara, however, began to chuckle. That horrid chuckle soon turned into a horrid laugh. "Interesting… We are not finished yet. You still have one more monster to defeat," she said, the maniacal grin returning to her face.
Though, Frisk simply stayed still. They made no advance towards the darkness ahead of them, where their new enemy most definitely resided. Their hands started to shake. Was this... not right... to explore their curiosity...?
They thought they were done. They thought it was over. They thought they wouldn't have to kill anyone else.
Chara frowned once more as her partner seemed to regain their gratefully discarded feelings.
"Are you not going to fight?" she asked, stepping closer to the trembling human. "Hmmm… How curious. You must have misunderstood." Chara couldn't help but grin her signature cheshire grin.
"SINCE WHEN WERE YOU THE ONE IN CONTROL?"
Chara's laugh echoed the room. The true extent of her soullessness presented itself as her eyes turned a heinous pitch black. A strange, otherworldly substance dripped from her eye sockets as her grin stretched farther than what should've been possible. She was not human, and even with a soul, she would never be.
Then, the darkness took over. Any attempt at resisting would be futile. The child of man, fallen from grace, advanced into the shadows.
In the throne room, there was only silence. Nobody came.
...
...
...
Isn't this what you wanted, Frisk?
If you thought I wasn't going to write more Gaster things after my year-long 19-chaptered project consisting of him as the main protagonist, you are surely mistaken lmao
Sorry, this is just a short little one-shot that stems from the thought of 'What if you got a phone call at the end of the genocide route like you did at the end of the neutral routes?' No fights here! So, here it is! Hope you enjoyed! :)
-Emily Believes xoxo