This au is a inspiration of GlitchTale and ScienceTale the main focus is on the things Frisk did

Once upon a time in a land far away where human and monsters once rule the land, a terrible war struck between the two race as they fight for peace, in the end the humans won and casted the monsters down underground and sealed them away with a magical barrier surrounding a mountain above the monsters underground and named the mountain Mt. Ebott, now 1 day a human child has found their way up to the mountain thanks to this folk tale that has been passed down for generations, the child was not cautious and slip and fell down into the entrance of the underground, what will they find down there? Let's see

After falling down the deep fall from the edge of the hole the child finally wakes up, they use all the strength they have left to lift their bruised body up, seeing how the impact of the fall was broken thanks to a bed of golden flowers that are beneath their body yet they stilled earned some scratches and bruises, the child tries to get up but fails, they try desperately to stand up yet each attempt fail again and again until they heard a voice coming towards their way, a adult female voice and another voice that they couldn't hear properly, now scared the child really tries to get up but keeps falling down, they want to hurry and get up to run scared to know if the stories of old are true that there are monsters underground that will eat humans, then the owner of the female voice finally reached them and they slowly look up to see a giant goat monster in a black and purple dress with a strange flower attaching its long roots onto her arm, the child slowly backs away as they see this monster before them

???: oh goodness! A poor human child has fallen down! My child please do not fear I will help you...!
###: n-n-no please...! Sta- stay away!!

Before they could do anything else the child passes out again from head injury, the giant goat look at the flower on her shoulder with a sympathetic expression as she carries the child in her arms.
Hours later the child finally wakes up to see all of their injuries healed a little and are even bandaged up, they look around to find themselves in a small comfortable bedroom and on the night lamp desk there was a piece of pie with a little note on it, the child took the note and look at the content written on it
"My dear child I hope you are feeling better once you awoke, here I made butterscotch cinnamon pie just for you, eat up and you can go meet me in the living room"
The child was confused, monsters can cook? They weren't sure if they should even eat the pie... What if its not actual pie ingredients? They slowly took the plate of pie and use the fork to take a piece and eat it, when the sweet flavor of pie enter their month they confirmed it was really a pie, a very delicious pie as well, they ate the rest of the pie and leaves the plate on the desk then continues their adventure to begin finding the living room, the child steps outside of the room and looks around, it seems like a nice small house filled with little cute monsters, they take the stairs up to see what could be up there and what on top was in fact the living room where the giant goat lady the child saw earlier was reading a book on the sofa, scared yet wanting to show how great full they are to the monsters kindness the child slowly steps up the stairs until the goat monster notices them, she takes off her glasses and stands up to greet the human child

???: my child your awake! Its good to see you all better now, how are you feeling?
###: u-um... Good...? I guess... I don't know I'm sorry... I'm just so scared and confused... Where am I?
Toriel: don't worry dear its quite natural to be scared in these kind of situations, your in my home right now, don't worry as long as we stay here your safe with me... My name is Toriel and this is my child Asriel

The child blinks as they look at the flower on her shoulder, it looked right back at them and waves its little leaf hand

Asriel: hi... I guess
###: ah! It talks?!
Toriel: yes... His situation is a little... Hard to explain but don't worry he's very nice once you get to know him!
###: i-i-i don't understand... Monsters are actually real... All this time I thought they were something people made up to get scared away by hunters!
Toriel: take it easy my child you are still healing, here have a seat, I know its all very scary from the beginning but I promise you everything will be alright...
Asriel: ehhh as long as they are willing to stay here with us that is
Toriel: Asriel
Asriel: what? I'm right aren't I? The rest keeps wanting to leave to go back up in the surface but we both know what truly happened to them
###: w-wiat there were others before me?!
Toriel: yes... I'm afraid so... I always hope they would stay a little longer... Alas young souls like yourselves always yearn for the outside world...
###: w-what... Happened to them...?
Toriel: they met the terrible fate of meeting the King of monsters... He is a merciless monster and will not stop at anything to break the barrier... Things just haven't been the same ever since Asriel...
Asriel: mom...
###: he's not going to let me leave so easily... Is he?
Asriel: no... No human has ever pass the barrier once they meet him
###: w- but your still here aren't you and your her son? T-there must be something you can do to change his mind!
Toriel: there is nothing we can do... He has the blood of many humans on his hands dear child... Thats why please... Stay here and don't go out there... You won't be able to survive the royal guards running along crossing his path!
###: I... I'm sorry but... I have to leave... I don't belong here with you... Or the monsters... I don't belong anywhere... But I still want to try...! If the king still has any apathy in him at all I still want to atleast try! I want to try and help him to listen! Even if I have to do it with my last breath...
Toriel: I... I understand... But its late right now and you should wait until tomorrow... Its better to be cautious of all his royal guards on duty... Ah I almost forgot... What is your name child?
###: I... My name is...

                          Chara my name is Chara