Lyra growled and turned to face him, and Kaya did the same, with much less growling. Gaster wasn't there.

"Think you can defeat me in my own world?" he asked, his voice echoing all around.

"I most certainly can!" Kaya spat back, her eye flaring in her eye socket.

Her white, glowing eyes appeared when she heard Sarisk ask, "Will you hurt him? What's that purple fume coming from in front of you?"

"Uh," she hesitated and turned around slowly, the tip of her tail twitching with uncertainty. "It's... complicated, lil' bro."

"Are you going to hurt him?" he asked again, with more seriousness hardened into it. His dark blue eyes gazed into her eye sockets, and she felt as if her little brother was staring deep into her SOUL, searching every part of it for a hint of harm.

"I'll try not to hirt him too badly, but no promises." She kneeled down to Sarisk and looked at him with the same amount of seriousness he eas giving her. "But you, try to understand that this is a real battle, not some silly game that's stress-free and whatnot. It's either Gaster is defeated by no means of killing... or I'm the one that is killed."

"But, can't you talk to him, like Mommy did with all the other monsters back when she was working to free them all?"

"Gaster's different. He-"

"What's so special about 'Gaster'?" Cypress cut in.

"I'll explain later, when we, I, have more time to explain everything. Now," Kaya said, getting up and facing away from them, a slight smile on her face. "I got to go kick Gaster's butt."

She teleported to the center of the large box she and her guardian were trapped in. Lyra came running towards her a couple seconds later. She slid to a stop beside Kaya, shadows billowing around her paws like dust.

So, what's the plan? Lyra asked. I doubt we can defeat him in his own reality, like I said earlier.

We have do to something though, Kaya responded, glancing at her guardian. We can stall him for as long as we can. Or, this may be some kind of test.

One testing our duration in battle.

Yes.

So we are to face his onslaught of attacks, never attacking ourselves because he'll hide from view in the dark and shadows.

Anything for family.

And anything for you, Kaya. I'll help out when you need me. For now, save your energy to last longer in this battle.

Alright.

With that, her guardian wolf disappeared. Kaya gazed around her, waiting for her grandfather's attack. It didn't come.

"What's the matter, Gaster?" she shouted, hoping teasing will make him come out or at least start his attacks. "Don't want to hurt a girl? A rare specimen? Don't you want to test my limits, see where I can no longer go on?" No answer, no attacks. "Intimidated by me or something?" Still nothing. "Come on out already, bonehead!" she spat, getting slightly frustrated, but very nervous and worried. What's he planning?! She wondered in desperation.

Out of nowhere, a blast of light gray came straight at her. Kaya leaped backwards, landing perfectly despite wearing heels, and the blast hit the ground, causing an exploson of shadowy dust. She covered her eye sockets for a brief moment before teleoporting over to the right, dodging a bone attack that came from the ground a few seconds later.

Just be careful, and don't. Get. Cocky, Lyra advised sternly, still out of sight.

I know. After all, we're still pretty early in the fight.

Did that stop your mom from dying?

What does it matter? Kaya asked, irritated, and dodged another blaster beam. Her guardian sighed.

You've still got a lot to learn.

Aren't you the same age as me?!

Same age in human years. Wolf years work differently.

So what? She dodged another set of attacks. How much does that actually matter?

It won't matter! Lyra growled. Now pay attention!

I have been this whole time! She summoned her own Gaster Blaster and fired it at the blast rushing towards her. Is this settled now?

Excuse me, it should be me asking that question to you! A moment of silence passed in her mind, but the outside was filled with loud cracks and crashes. Yes, fine. It's settled.

The intensity of Gaster's attacks never changed. It never got any harder; it was actually pretty easy to Kaya. It certainly seemed like a test now.

She dodged multiple blaster beams, trying not to use much of her energy by teleporting. "This is a test, isn't it?" she shouted out during a recovery moment. She summoned bones from the ground that acted like a shield above her from bones that rained down over her. Sweat started gathering on her skull.

"Did it really take this long to realize that?" Gaster said, appearing a few yards away.

"I had thought of it before, but now I know that it is." Her eye's 'fume', as Sarisk had called it, acted like fire, going this way and that, and never ceased.

"Well then, do you want a harder test?"

Her fuming eye socket went out, and she smiled. "I would prefer no more tests," she said, stepping aside. Her guardian appeared, equipped with a Gaster Blaster on her head, and blast a beam of bright purple light. Gaster was shocked by this, she saw that for a split second before the blast hit its mark. Instead of the shadowy dust that would normally explode up around the blast, it was a pale gray.

The blast ended and Kaya's white eyes appeared in her eye sockets. The blaster on Lyra's head disappeared, and they watched as the dust settled, revealing no sign of Gaster. Kaya's eyes got slightly smaller and shook in her eye sockets.

"Where'd he go?" she whispered, for fear that she had actually killed him.

He couldn't have d-died, her guardian said. C-check your LV. I'm s-sure that you couldn't have killed him. The stammer in her voice made Kaya even more worried and fearful.

She summoned her SOUL and checked both her LV and HP. Her LV hadn't increased, so Gaster was alive, and her HP was just a sliver:
.5/10HP

You fool! Lyra growled in her head. I told you to be careful!

I didn't get hit by anything, if that's what you mean! It was low before we got here, and crashing onto the ground must've made it this low. Either way, Gaster's alive and I don't know if he's done testing or not.

As she finished saying that, a bone came flying at her SOUL and pierced it. Luckily it was blue, so all she had to do was not move and she wouldn't take any damage. She thought wrong. The bone turned orange in an instant, and started taking HP away. Kaya gasped and jumped away from it, clutching her chest.

"Don't ever underestimate your opponent," Gaster said, his voice echoing with no sign of his physical body. "Don't show your SOUL in the middle of combat unless you know you're safe." With each piece of advice, a Gaster Blaster would appear and fire at her. She almost managed to dodge the first one, her jacket getting a large tear in it, and teleported away from the second. "How stupid can you be?" he asked as he appeared in front of her.

She gazed up at her grandfather, slouching from pain and exhaustion. "Appearently not as stupid as you!" At this, her eye ignited and she pulled Gaster to the floor with her own telekinesis. She kept him there, despite whatever he threw at her and her exhaustion. Eventually he gave in to her powerful magic.

"Alright, you got me," he admitted. "Are you going to kill me now?"

"Am I going to kill him, he asks. How stupid do you think I really am? Of course I'm not going to kill you." She released her magic and wearily watched him turn around to face her. Her grandfather looked saddened and defeated. Looking defeated she understood, but looking sad she didn't.

"But you have every right to kill me. So why don't you?"

"This is your reality, first off. You can change and bend it how you will. Second, I can't get it past me that we are family. And third, anyone can change. Look at Aunt Chara. She, Mom, Uncle Asriel, and Dad are the only ones who remember past runs, Mom and Aunt Chara being the ones who remember most. She's doing fine in our pacifist route. You know that there have been multiple runs of genocide, and that kind of thing can really twist people. Maybe forever. But Aunt Chara is learning to cope with it. From the stories, she's doing much better than when she was first given half of Mom's SOUL to exist. I believe you can change as well. It might be a long time to completely adjust, but there is always room for adjustments."

Her grandfather stared at her in disbelief for a second; his eye sockets swelled up with tears the next. Kaya offered her hand to help him up. He accepted it and was standing a moment later, a broad smile in his skull. "Thank you, my granddaughter," he breathed out. "I will try my best to change and fit into your world."

"You don't have to fit in, Grandpa Gaster. You just have to be yourself, with the adjustments to being a better monster."

"You are much too kind when you plan to be."

"I guess I get it from Mom. She, Uncle Papyrus, and Sarisk are the-" Her eye sockets went dark as she realized something.

"Are you alright?" her grandfather asked uncertainly.

"Sarisk! Cypress!" she shouted a moment later. "They're probably worried sick about me!" She teleported over to the wall she thought she had left them, but the fight had messed up any sense of direction. That and the walls were invisible, so it would be quite impossible to remember where exactly one wall was and where it ended. She heard Lyra sigh in her head.

Shut up and help me, will ya?!

One, I only sighed. And two, you're in the opposite corner.

How can you and Gaster know every spot of the Void?

Gaster's been here for many years, and I just have an adept sense of direction.

So, how do you expect us to get out of here anyways? Kaya asked her guardian as she teleported to the opposite wall, finding her brothers on the ground, staring up at nothing. They've spent too much time with Uncle Mettaton and Blooky, she added in her own mind.

Well, Lyra started, appearing beside her and nudging the two onto their feet, the invisible barriers appearently gone. Gaster manages to go to our world, and we can't see him because his body had been lost to time and space. But since he pulled us in, and we have physical bodies awaiting our arrival, everything should be fine; as though we were only trapped in a dream and going back is like waking up.

"Is Gaster okay?" Sarisk asked, breaking into their conversation without knowing it.

"Yes, I am fine, child," Gaster said, appearing beside Kaya. Her tail raised slightly in an arch and her eye sockets went dark for a moment, scared from his sudden appearence, although she should've been used to that.

"Should we let the truth carry on to them?" Kaya asked her grandfather, slightly acting like her brothers weren't there.

"As long as they can keep it secret," he replied. "We both remember how well that worked out with Sans."

"Yeah," she agreed while her twin asked, "How do you know our father?"

"That's the secret that you can't tell anyone else about. He's our grandfather, making him Dad's and Uncle Papyrus' father."

"I sort of figured he was some relative of ours, especially since he seems to be the one Paps doesn't remember and Dad refuses to tell us about."

"Yeah, and Grandpa Gaster, how do we get out of here exactly?"

Her grandfather glanced at her, looked sad for a moment and said, "Just teleport home. You know your destination, so it should be no problem getting back. And you habe physical bodies waiting for you outside this void."

Just as I thought, Lyra said.

Yeah, but we didn't know exactly how to get back, Kaya replied. It was only an assumption.

Yes, but it was the right assumption.

"Thank you," her little brother said suddenly, going up and hugging Gaster, who was about four times his size. He picked Sarisk up and said, "You're welcome, my little grandson."

"Will we see you again?"

"I will try to come and visit you, but both of your dreams are much harder to get into than your sister's nightmares."

"They're still going on?!" Cypress yelled. "I thought you tokd me they stopped a long time ago!"

"I don't want somebody fussing over me my whole life!" Kaya argued back. "I had to come up with something in order for you to stop."

"But I don't like having secrets being kept away from me!"

"Then argue that with Dad. He's the one who hadn't told us anything about our grandfather!"

She heard Gaster sigh and bones erupted from the ground between them.

"Will you be more careful?!" she whisper-shouted. "Remember how low my HP is!"

"Alright, how about I get you home?" he replied out loud and placed his free hand on Cypress' shoulder. Kaya took hold of her brother's arm and her grandfather teleported them out of their dream state. She saw her brothers disappear in the time between, meaning that they had gone back to their bodies, and then stared at Gaster.

I can't let him stay here, she thought furiously. It's not right and fair and he deserves to be with his family.

He looked at her with a saddened expression, only for it to turn into surprise when she grabbed his arm right before the teleportation ended.

Everything was enveloped in a bright light, then sudden darkness.

They had gotten back to their reality, and it was dark out. Kaya popped out of the air and landed on her bed with a soft thud. Gaster did the same, except he landed on the floor with a much louder thud.