Frisk and Asriel "mind-chatted" for what seemed like an eternity, Asriel told them about Toriel, their dad, and Chara's life as a family. They also let them know about the painting on the wall, and the necklace Frisk just noticed on Chara's neck. Asriel started fading into Frisk's mind, and so they bided farewell to their new friend :
"You take good care of them, Frisk. They might seem scary and a bit on the bad side, but they are the best friend I've ever had."
"They are taking care of me more than I do, I hope I can be of use in the future."
"Stay determined, Frisk. You are doing them much more good than you think you are "
Asriel disappeared, and what was Frisk facing now was an angry Chara. They were embraced for too long, and although that helped calm them down, Frisk was getting too touchy-feely and Chara was not comfortable being into fluff for too long. They motioned a knife slice, to which Frisk smiled and showed theirs, but Chara burst into laughter.
"Hey Frisk, do you think you can hurt me with that?"
"I can at least fake hit you a bit for fun I guess !"
"I'd like to see you try, that would be certainly fun."
"Sure thing." thus Frisk started swinging his newly acquired weapon toward Chara, who dodged effortlessly. It was akin to child's play, but the Fallen did not mind leisure like they used to do with Asriel.
"Hey Chara, stand still for a bit." Frisk panted a bit and has not landed a single strike. Chara giggled, mocked their pursuer with their tongue, and kept on dodging until their back was against the wall. They allowed Frisk to score a hit, smiled at them and gave them a false punch.
"Congratulations on hitting me once, you'll have to pay the price now."
"Wh-what would that be?"
"Chocolate, of course. Unless you want me to hit you, child."
Frisk sighed, Chara sure was fond of sweet things. They ran over to the house, went to the fridge, and grabbed whatever chocolate bars were there. Chara followed them and made sure Toriel was still having a nap. Frisk eyed the book Toriel was reading and read something about snails. Chara giggled at the Child's trying to associate goats with snails without much success.
They both went back upstairs, and the Fallen took the bars after politely thanking Frisk.
"I saw Asriel again!"
Chara almost choked on their sweet prize:
"Again? It looks like my brother likes you more than me now."
"They are really nice, and they told me so much about you."
"..."
"Chara?"
"Yes child?"
"Your locket, Asriel told me about it too."
" Oh that ... is the best thing they left me before I screwed up everything"
" Would you like to talk about it, Chara?"
"Asriel did not tell you about it?"
"They faded before they could tell me more, and they said I was useful."
Chara wondered why their brother would say that until they felt their SOUL glowing again at the words. Yes, that human was special.
"They are right. You are more useful than you think you are ... I'll tell you more about what had gone wrong and got both of us both killed."
Chara went on their story of them accidentally poisoning their father. They had no butter to bake a pie and thought butterscotch would replace it so they added some. Their father fell ill after eating the butterscotch pie and they were deeply hurt by it. They thought Asriel would be devastated by the news so they laughed it off to ease their pain. Toriel had a hard time forgiving them for that, but could not hate their child for something they did not mean to do. Frisk understood how they felt, they also laughed off being bullied not to be demoralized, although that did not work all the time.
Chara cried a bit while telling the child about their plan of leaving the Underground, and how they got to commit suicide before involving Asriel in bringing them beyond the barrier. While that permitted their brother to go to the surface, it also got them killed. Chara felt so much guilt they materialized their knife and felt like hurting themselves again, Frisk took the hit instead while hurrying to stop them from wounding their already profusely self-harmed arm.
"Child...?" Chara was confused at their companion taking another scar. They've already defended monsters, tolerated their badmouthing, and now were hurt again by their own hands Frisk cried too, from pain, but smiled at the Fallen. They took Chara's bruised arm and showed their newly acquired scar.
"I promised Asriel to take care of you so I cannot let you get hurt."
Frisk did not expect Chara to jump at them for a hug, as the Fallen wept their now-deceased brother and smiled at being taken care of by a younger Child. Frisk returned the hug tighter, SOULs happily glowing red at an embrace that went on forever.
Toriel, who had a nap near the chimnee, woke up a little worried. She had a dream she never had before. She felt a heartache at her now ex-husband playing with her two children. That occupied her mind until she heard weeping upstairs. She ran down the stairs and barged into the room, worried about the Child crying on their own, only to find two of them :
"Cha ... ra, Chara !"
"Mo-Mother ...?"
"I ... I ... I am so happy to see you alive and well my child !" while she held both children into her arms Chara thought of escaping again but had no strength to do so, and was held on by a determined Frisk.