And here's the next chapter! I'll try to speed up, or at least keep more steady, the updating process.

Big thanks to Dragonsrule18 for reviewing so nicely on this story along as the one-shots! I'm glad you love them, and it gives me more motivation to keep updating. :)

Papyrus took care to put Sam and Piper to sleep. It wasn't a easy task, because the twins were shaken by what happened to Noelle. The thought of their mother being put to hypersleep while her SOUL was ripped out and in the possession of Flowey, made them feel scared. Sam was also angry and kept repeating that he should've gone with Frisk after Flowey. But Papyrus tried his best to reason the troubled boy.
"THIS IS WAY TOO DANGEROUS, SAM. FRISK HAS A WIDE EXPERIENCE IN BATTLING, WHILE YOU HAVE NONE." - Papyrus said - "FRISK DIDN'T EVEN WANT ME TO COME WITH HER, SO SHE DEFINITELY WOULD HAVE REFUSED TO TAKE YOU WITH HER."
"He's right, Sam." - Piper added with a quiet voice, as she hugged a pink bunny plushie to her chest - "Flowey would kill you… He already hurt Noelle very badly, I don't want something happen to you too."
"Uh, you're right, Piper… But it's just that… urgh!" - Sam let out a frustrated grunt.
Papyrus adjusted the covers over the kids after what he sat down on the edge of Piper's bed and tried to reassure them, taking his confident tone.
"YOU SHOULD BE POSITIVE… I'M SURE THAT IN THE END, EVERYTHING'S GOING TO BE ALRIGHT AND NOELLE WILL WAKE UP. YOU JUST HAVE TO BELIEVE."
"Believing doesn't make things true…" - Sam remarked.
"WELL, I THINK THAT'S EXACTLY WHAT EVENTUALLY MAKES THINGS TRUE." - Papyrus replied with a smile.
After a moment, Piper asked:
"Are you scared right now, Papyrus?"
"I... I, THE GREAT PAPYRUS, AM NOT SCARED OF ANYTHING... EXCEPT WHEN IT COMES TO MY FAMILY." - Papyrus admitted as he looked down, then he looked back at the kids - "YES, I'M SCARED FOR BOTH NOELLE AND FRISK NOW. B-BUT I DON'T LET THIS GET TO ME..! I STAY STRONG FOR THEM AND FOR YOU."
"It's nice to hear…" - Piper smiled at him, before closing her eyes - "If you belive, then I'll believe too."
"THAT'S THE BEST THING TO DO RIGHT NOW, PIPER." - Papyrus said with a nod.
"I don't know… I'm afraid that our faith and efforts may not be enough." - Sam said with a sad voice.
"FAITH ISN'T EASY... AND THAT'S EXACTLY WHY IT'S POWERFUL."
Sam thought about it for a second. He guessed that Papyrus' words made sense. The boy then finally allowed himself to close his eyes and exhaled slowly to ease some of the tension in his body. Papyrus got a small smile and then went to plant a kiss on the children's foreheads. When he left their bedroom, he thought to himself: "FRISK... I HOPE YOU'RE ALRIGHT OUT THERE… PLEASE BE ALRIGHT."

Meantime at Home, Frisk was staring at Asriel with a shocked look. He was back. He looked almost like his "God of Hyperdeath" form, minus the evil eyes. Asriel was thus a grown up young goat monster. Last time Frisk has seen him, Asriel was a thirteen years old boy. But now, he seemed to be around her age.
"Asriel… You're back… How… How can it be..?" - Frisk finally managed to ask.
"I... I'm not sure, but I think it's because your daughter's half-monster… and so, her SOUL's different…" - Asriel answered, then lowered his head in remorse - "Argh, I should never have done this…! This was a twisted and horrid idea… very Flowey-like, actually. I am so very sorry, Frisk. I can apologize a hundred of times, but it won't change that I killed your daughter."
Asriel then sat down on his old bed and put his face between his hands. A tear slid down his face and he started to shake a little. He hated himself, he was a murderer. He had been one before, but now he knew he went too far. Frisk then sat down next to him and put her hand on his arm. Asriel flinched a little and he didn't dare to look Frisk in the eyes.
"It wasn't really you who did it…" - the young woman started - "And Noelle isn't dead."
"She isn't…?" - Asriel asked with a frown, turning his head to Frisk - "But it's impossible. I ripped out her SOUL."
"Noelle's hanging between life and death. But after you left with her SOUL, she was still breathing. There's no mistake she's alive. Her SOUL is apparently strong enough to be still connected to her body." - Frisk explained.
"This means... it's not too late after all." - Asriel said to himself.
"...It isn't." - Frisk confirmed, then let out a sad sigh - "Asriel, you know why I came here, right…?"
"You came in hope to get Noelle's SOUL back."
"I... I really hate to ask you this… I don't want to ask you this… but…"
Frisk didn't dare to finish. There was no way she could say it so it would sound right. She swore to herself she'd fight for her daughter's life until the end, but at the same time Asriel was a friend, a brother. Frisk couldn't just ask him to give up on his life. Asriel guessed her thoughts, so he gave her a sad and sorry smile.
"It's alright, Frisk… I... I'm supposed to be dead anyway, right..?"
"Asriel..."
"I'll be fine. Really." - the goat monster forced his smile through appearing tears - "Your daughter is a hero, she deserves her life more than I deserve mine. Noelle has so many things to live yet… My only regret now is that I could never properly know her…"
"No... No!" - Frisk shook her head and held Asriel's hand tightly in hers - "There... there must be another way. Years ago, you… no, Flowey, told me that in this world, it's kill or be killed. But we both figured out there was a third way - mercy."
"I'm glad to see you haven't changed. But there's nothing that can save us both." - Asriel looked down - "Since I have not much of a life left, let me at least do one last right thing. I want to give Noelle her SOUL back."
Frisk closed her eyes and slowly nodded, fighting back her tears. She thought it wasn't fair that Asriel came back to life only to be gone again… for the second time. The young prince never deserved to die in the first place. Why was fate so cruel to him? It was painful for Frisk to see him go away again. And on the other hand… Frisk wanted her daughter to live. Noelle was one of her reasons to live, she was what was worth to fight for. Frisk already lost her once, she refused to lose her again and definitely.
Asriel inhaled deeply and exhaled longly. He didn't exactly feel ready. Yet, who in his place would be ready? But it was the right thing to do. He had the courage to sacrifice himself once, he would do that again. Asriel was about to release the SOUL that was within his body, but then… his eyes widened a bit as a thought crossed his mind. Frisk noticed the change of his facial expression.
"What's the matter, Asriel?" - she asked him.
"Flowey will never stop." - Asriel said with a gloomy, yet subtly scared tone - "He won't learn anything from today's experience. After I release Noelle's SOUL and become him again, I might keep my distances with the world at first, but I'll start plotting quickly enough. Just like it happened the first time."
"Come with me." - Frisk said almost immediately.
"W-what..?"
"Come with me, Asriel. Keep Noelle's SOUL for the time being. We can try to find a solution meanwhile. Maybe there's a way to somehow maintain this form or make you feel things when you're Flowey… a solution must exist. Gaster might find one."
"No, no, we can't…!" - Asriel protested, alarmed - "I... I can't come with you! We'd have to go through our parents' house and… I just can't face them. Not after everything that I've done…"
"Look, I get that you're feeling bad about your actions, but facing them is unavoidable. Like you said, Flowey won't let Noelle alone. He'll come back and might hurt other people from our family. We must do our best to prevent this." - Frisk said seriously.
"You can't force me to see them! You respected my will last time..!"
"This time, however, it's not just about you, Asriel." - Frisk replied, still sounding serious - "It's about Noelle, my daughter and our parents' granddaughter. They deserve to know the truth. Besides, you said yourself you want to do things right. And in our situation, doing things right implies to go in the outside world and face your family."
Asriel lowered his head, then clenched his fists on his robes and he started to shake.
"I can't... I can't... Not after I..."
Frisk sighed. She surely felt sorry for him, but she couldn't allow him to run away from his problems this time. She picked her cellphone from her pocket and Asriel's eyes widened as soon as he saw it.
"Are you calling Mom and Dad? No, don't do that!"
"Keep cool, it's not them I want to call." - Frisk said with a sigh - "I'm calling my husband."

While Frisk and Asriel were having their conversation in the Ruins, Papyrus got one with Gaster. After the kids fell asleep, Papyrus went to the room where his unconscious daughter was. Gaster was still there, making sure he and Alphys had stabilized her right. He'd have to watch carefully Noelle's vitals the next few hours, probably the whole night. When Papyrus entered the room, Gaster looked up at him, aknowledging his presence, but didn't say anything. Papyrus sat at the edge of the bed and then gently stroke Noelle's face. He frowned a little, because even through his glove, he could sense there was no warmth in his daughter. This made him even sadder. Gaster watched the little scene and was amazed (but not surprised) how much Papyrus cared for his child. He could litterally read the pain, sadness and love on Papyrus' face. The latter's eyesockets then glowed purple.
"She will live, Papyrus." - Gaster said.
Papyrus looked up at Gaster, who spoke again.
"I won't let her die. I will make sure she lives and returns among us."
"YOU... YOU REALLY MEAN IT?" - Papyrus asked.
"...I do. I know it has always been… erm, 'complicated' between us all, but I'm not totally indifferent to the lives of your family." - Gaster replied, his tone difficult to read.
But despite Gaster's almost casual way to say it, Papyrus saw more in those words and his eyes rounded in wonder. He could see at that moment that he'd been right all along about Gater; that there was some good in him. Papyrus just got another proof that Gaster was a better person than what he let on. He's been right to believe in his creator after all... just like Noelle had been right to give him a second chance.
"YOU KNOW... NOELLE WAS VERY UPSET THAT SHE ARGUED WITH YOU." - Papyrus said - "AND WHATEVER SHE SAID TO YOU EARLIER, SHE DIDN'T REALLY MEAN IT."
"Good to know, I suppose." - Gaster replied with a sigh.
He just wasn't sure what to say in this situation. Gaster already hated to admit that Noelle's words affected him more than it should have. And now, when Papyrus told him that Noelle didn't really mean it, had a strange effect. It was almost as though the cracks on his SOUL received a treat. But at the same time… Gaster knew there was truth in Noelle's words. She was right, when she said that he didn't deserve Sam and Piper. Noelle was a much better person than he was. Thus, even though Noelle said it just out of anger or frustration, this didn't make the words less true.
"UH... DID I SAY SOMETHING WRONG..?" - Papyrus asked with light anxiety.
Gaster looked at Papyrus and saw that his expression was similar to the one he used to have back when he was his test subject. Like when he feared punishement or any negative response from him. Gaster sighed and replied:
"No... you didn't. I'm just not sure what to make of it. Because regardless of Noelle's intentions, what she said is true."
"OH... BUT EVEN IF IT IS, NOELLE STILL DECIDED TO FORGIVE YOU AND HELP YOU THROUGH HARD TIMES. THIS MEANS SHE BELIEVES IN YOUR BEST SIDE. THIS IS WHAT TRULY MATTERS."
Gaster didn't say anything for a moment, as he processed what Papyrus said. He was right; except for the argument that happened in the evening, Noelle had always been only well-meaning and helpful towards him. The thought of it made Gaster want to ask Papyrus a question that had been bothering him for years now.
"Papyrus, I... um, there's something I've been curious to know for a while…" - Gaster started awkwardly, and Papyrus waited patiently for him to finish the question - "Before the De-Code, you've sent me a photo… of young Noelle. Why…?"
"I... I DON'T KNOW. I JUST THOUGHT THAT MAYBE... JUST MAYBE, YOU'D BE… INTERESTED TO KNOW..?"
The anwser was pretty simple, yet it said a lot. Gaster got a shadown of a smile on his face, before replying:
"Your assumption... wasn't wrong."
Papyrus' eyes shone and he smiled. At that moment, his cellphone rang and he felt relief to see it was from Frisk. He answered the call, exclaiming:
"FRISK, THANK GOODNESS YOU'RE OKAY! SO, WHERE ARE YOU RIGHT NOW?"
A silence followed, as Frisk was speaking to him on the other end of the line. Papyrus then got a surprised expression oh his face, before asking:
"THE PRINCE ASRIEL IS ALIVE..?"
Gaster's eyes widened in shock when he heard those words. He silently instructed Papyrus to put the conversation on loud speaker. Papyrus did as asked, and thus the two skeletons could hear what Frisk had to say.
"Y-yes, I know, it sounds all crazy…! Flowey always had Asriel's memories, being filled with his dust, but he… he couldn't really be himself unless absorbing enough SOULs… Anyway, now he absorbed Noelle's SOUL and it was enough to make him regain his true form! I'm not sure how it happened, but it did..!"
"I know how." - Gaster said - "It's because Noelle's SOUL is hybrid and it contains magic, and since monsters keep themselves together thanks to magic, her magic permitted Asriel to… reform himself from his dust."
Since Frisk couldn't understand Gaster, Papyrus took care to translate her what he said, being able to understand wingdings.
"I see... But that's not the problem now. I was wondering if there's a way to save both him and Noelle." - Frisk said - "At first, Asriel was willing to give Noelle's SOUL back, but then he said that he'd come back hurt us once he becomes Flowey again. So… is there any way to maintain Asriel in his current form?"
Papyrus looked up expectingly at Gaster, who got a thoughtful look. He was impressed by the human's will to save the young prince along with her own daughter, but he also remarked how challenging this puzzle was. The current state of science made clear there was no way to artificially create a monster SOUL. Alphys herself had explored all the possibilities human SOULs had to offer in the form of determination. A research that had castastrophic results. But now… with a hybrid SOUL, new possibilities could be exploited.
"There maybe is a way. But that's a big maybe." - Gaster said - "The only way to find out is to study more deeply the properties of Noelle's SOUL. It's not something that can be esily done considering I'm prone to restrictions. And besides… I don't think any of you want me to even touch Noelle's SOUL…"
The doctor's answer created a pensive atmosphere. Papyrus was the first to answer.
"BUT IF YOU DO SCIENCE TO SAVE PEOPLE AND NOT HURT THEM, I THINK I CAN ALLOW YOU TO… SEE NOELLE'S SOUL. AS LONG AS YOU DON'T HURT HER, OF COURSE."
"I'm of the same opinion." - Frisk said - "As long as you don't go too far, you can study the SOUL. I just want my daughter back, without anyone getting hurt."
"SANS WON'T LIKE THIS THOUGH... AND HE'LL SURELY WON'T LET YOU HEAR THE END OF IT…" - Papyrus then remarked - "BUT I'M SURE THAT WHEN HE SEES NOELLE TO BE OKAY, HE'LL CALM DOWN AND CHANGE HIS ATTITUDE!"
"I'm not so sure of that... Sans tends to give more importance to bad actions than the good ones." - Gaster said - "But it's not Sans' consent that truly matters. It's Asriel's and… Noelle's. We'll discuss this later. For now, Asriel should just return home."
Papyrus translated the statement for Frisk, after what the woman exposed the problem.
"The problem is that Asriel doesn't want to follow me. He's so ashamed of his past actions that he refuses to ever see his parents again. He simply refuses to leave the Ruins. How can I convince him to come with me..?" - Frisk asked.
"HMM... YOU SAY HE'S ASHAMED OF HIS ACTIONS. SO YOU JUST HAVE TO TELL HIM HIS MISTAKE CAN MAYBE BE FIXED. THAT MAYBE HE WON'T HAVE TO EVER MAKE BAD THINGS ANYMORE, IF HE JUST GIVES IT A CHANCE." - Papyrus suggested.
"...Alright, I'll do that. Don't worry, Papyrus. I have no intention to return without him. I will convince him, no matter what he says. And we will save our daughter." - Frisk said, sounding determined.
"I'M GLAD YOU HAVE FAITH. I HAVE FAITH TOO. I'LL BE WAITING FOR YOU, FRISK. AND NO MATTER WHAT HAPPNES, PLEASE BE CAREFUL." - Papyrus pleaded, then cut the loud speaker and said in a quieter tone - "I LOVE YOU."
"I love you too, Papyrus." - Frisk replied, her smile heard in her tone, before hanging up.
Papyrus put the cellphone in his pocket, then saw Gaster give him a weird look, which embarrassed him a little. Gaster then asked, even though it shounded more like a statement:
"You and the hum-... Frisk really care a lot for each other, don't you?"
"WHY, YES." - Papyrus replied with a light blush - "THAT'S WHY WE GOT MARRIED AFTER ALL..."
Gaster grinned a bit at the obvious statement. Then, looking down at his computer screen, he said:
"I hope Frisk gave you what you needed."
"SHE DID." - Papyrus confirmed, then looked down at Noelle and added with a little smile - "...AND SHE GAVE ME EVEN MORE."
The former Royal Scientist just nodded in response, satisfied by the answer.

In the Ruins, after Frisk hang up her phone, she returned to Asriel's room. She saw that the goat monster looked very troubled. He was sitting on his bed, his hands clutching his forehead and he was shuddering. This worried Frisk, so she asked:
"Asriel? Are you hurt...?"
"Gnhh... My head... It's invaded by... a foreign voice..." - Asriel answered - "It's Noelle's voice..! She… argh, she's scared, she's angry and me… and she's sad…"
"You mean, you... you can hear Noelle talking to you..?" - Frisk asked with a shocked expression.
Asriel only nodded, not finding the strength to speak.
"You murderous monster! You killed me!"
"N-no... I didn't want to... I'm sorry..." - Asriel said.
"Liar! You've craved for my SOUL since my birth!" - Noelle's voice reasoned in his head again - "You took away my life! You took away everything from me! And I'm doomed to live in your body forever!"
"Please... stop." - Asriel begged as a tear fell from his eyes - "...I didn't want it to happen… I didn't… I..."
"Asriel, what is she saying..?" - Frisk asked as she sat next to him.
"She's mad at me for k-killing her..." - Asriel answered.
"Asriel... Noelle..." - Frisk put her hand over the prince's chest - "Noelle, if you're really in here, please hear me… I'm sorry I couldn't protect you… and I'm sorry you had to 'load' because of me. But please try to calm down. I... I understand your anger, but Asriel has suffered enough. He's not really Flowey, he would never have done this to you. And… you're not really dead, Noelle. Your body's safe at Gaster's house. We can still save you… maybe even you both."
Frisk then looked in Asriel's eyes, her hand never leaving his chest (as if still holding her daughter), and pursued:
"I was speaking with Gaster. He said that there's maybe a way to keep you alive in this form. Gaster needs to understand better the properties of Noelle's SOUL to know for sure. But this means you'll have to come to the Surface with me."
"I have no choice but to see my parents… and everyone again, right?" - Asriel said, sounding defeated.
"You don't want to see them because of your mistakes. But here you have a chance to fix some of them." - Frisk said, before adressing to her daughter - "And Noelle… I know you're scared, but I promise that wether or not we find a way to keep Asriel alive, we'll put you back in your body."
"Frisk... I'm very scared… What if Gaster hurts me?" - Noelle spoke in Asriel's head.
"She's afraid that Gaster might hurt her." - Asriel transmitted her thoughts to Frisk.
"You don't need to be afraid, my darling. Gaster and I already discussed the matter, and he will not hurt you. Your father and I will be there to make sure he won't. Gaster only needs your consent - yours and Asriel's."
A pause followed. Frisk looked at Asriel expectingly, waiting for his answer. Then, Asriel made his decision, looking straight into his sister's eyes.
"Alright, I shall come with you. I'm done running away from my problems. I must face them and the consequences of my actions." - he said with resolution.
"All right, I guess I can trust Gaster... I didn't give him a second chance for nothing, after all."
"Noelle wants the same thing." - Asriel said.
"I'm glad you both made the right choice." - Frisk replied with a smile.
Frisk and Asriel then stood from the bed and walked out of the old house within a minute. They walked silently long the corridor until they made it to the dark room before the exit from the Ruins. Frisk was about to exit, but she noticed that Asriel didn't move. He was standing at the spot beneath the hole on the ceiling. The dark starry sky could be seen from there. But Asriel was staring on the ground. Frisk approached him and asked what was wrong.
"This is where we met for the second time… This is the exact spot where I was when I tried to tempt you with my 'kill or be killed' philosophy…" - Asriel said with a distant tone - "Where I could've pulled you down on that evil path…"
"But you didn't." - Frisk took gently the goat's furry hand in hers - "Flowey's your past. Try to think about the future."
"Ha... It's not certain I have one..." - the prince let out a sad chuckle.
"Well, let's go and find out together?"
Asriel managed a small smile and nodded. After that, the two young adults finally exited the Ruins. Whatever came next, they were ready to face it. They'd do it for Noelle and for the family in general. Asriel and Frisk decided to stay determined and have hope. Because hope was the most powerful thing in this world.

A/N: So, there's a lot about believing and third ways... a very OUAT-like chapter! :)
Now, is there hope for Noelle and Asriel? Can a way be found? Or will the family be forced to make the difficult choice?
Toriel and Asgore still have to meet their son...

And yay, Gaster and Papyrus could finally have a conversation together! :D I've been very excited for the moment when Gaster would ask Papyrus about the photo.
In case you forgot, he's referring to the photo mentioned in the 3rd chapter; a photo of a three years old Noelle and with the words "YOUR GRANDDAUGHTER" written in the back.

Oh, and the reason why Noelle started to manifest herself within Asriel later, it's because there was sort of a... "adjusting time"? After Noelle (or rather her SOUL) was absorbed, she wasn't exactly conscious for a while until she came out from her state of slumber and confusion (while Frisk was talking in the phone).