Minato teleported back to the holiday home with a weak Kushina in his arms, he had managed to save both the babies, Kushina however still had the nine tails taken out of her, she was bound to die unless it was restored.
Minato would tuck her in the bed where Naruto and Menma slept, the infants stirred a bit from their slumber.
'Damn, no wonder babies always sleep, I feel just as strong as a twig' Menma thought.
As Minato tucked in Kushina he would reassure her "You'll be fine, I promise" he says, 'Liar...' Menma thought and Minato put on his hokage garment, Menma always wondered how it was going to help when he watched when he watched Naruto as a kid. as Minato teleported away, Menma would turn to Kushina as she hugged him and his brother.
"I'm so sorry..." She says in a whisper that made a lump form in Menma's throat, he would internally sigh 'I hope this works'
Back in the womb, when the voice in his head he named Alex, would help Menma understand the basics of chakra and negative energy, through the months he would experiment by sending waves of chakra and negative energy from the womb and observe Kushina's reaction. He would listen to hear what happens outside and hear Minato having to deal with Kushina's sudden mood swing, he silently apologized to his yet to be father and continued experimenting, even attempting to communicate with Kurama, they had a brief conversation but, after that they didn't exchange any words after a few threats of someone eating the other. So basically Menma had a theory that if he combined negative energy with a healing technique, by doubling the amount of negative energy, he would get positive and when he combined that with his healing technique, he would amplify the ability, as for positive energy, he discovered this last time he heard Kushina suddenly being happy as Minato was in utter bewilderment.
Menma would internally sigh 'Minato, Kushina and practically the whole village will owe me if this works, if not, I suppose we're all f####d'
He'd take the deepest breath he could with his tiny lungs and focus negative energy in his palm, then double it he would pour his healing ability into his small palm and put his hand on Kushina's neck.
Kushina felt an unnecessary surge of happiness that died down as Menma's healing technique kicked in, she felt better, not as good as when kurama was inside her, but she didn't feel like she was moments from death anymore.
Her eyes widened as she looked down at Menma, Menma would pass out, Kushina checked him to make sure he wasn't dead, Wich he wasn't, she held him up and asked the unconscious infant.
"Did... You do that?" Naruto would sneeze as soon as her words came out, she scooped Naruto up.
"Aw, I'm sure you had something to do with it too" she smiles as she looked down at her sleeping new borns.
She'd shake her head "Come on Kushina, the village is in trouble" she muttered to herself and scooped up bother the children and ninja ran out to where Minato fought the nine tails.
Minato looked back as he noticed her, he'd blink rapidly to make sure he wasn't hallucinating.
"You're supposed to be in bed! How the heck are you-!" He was cut off as a tail smacked him away like a fly, he crashed into a tree trunk, Kushina would come to his side.
"Minato!"
"I'm fine..." He mumbled as his body peeled off the trunk, he would turn to Kushina
"How are you...?"
"I think I'm okay, well I don't think I'm dying anymore, I think Menma had something to do with it" She'd hold out Menma, leaving Minato on utter confusion, he wondered if it was him going mad or the whole world.
Kushina shook Menma slightly, trying to get him up, she grabbed Minato's hand and make it envelope Menma's, Menma would focus hard and pour as much negative energy he could, but in the form of chakra.(Note: Negative energy is the emotions, Negative chakra is the power source, in my book at least)
Minato felt something dark, he'd fuel the mysterious chakra with his own chakra, and a dark Navy blue energy would surround him, he felt all of his flaws dissapear, his hesitation, all the distractions, it felt like it was just him and the nine tails, he no longer fought with duty, but with wrath, he would add the dark chakra into a massive Rasengan and drop it into Kurama.
"Now!" He shouted, and Kurama was enveloped in adamenting chains, fueled by Menma's Negative chakra, and she began to pull Kurama in.
"NOOOOOOO, NOT AGAIN, NO" Kurama howled but was pulled in all the same, and Minato would repair the broken seal on Kushina's belly, they checked Menma after their chakra cloaks dropped, he was sweaty and a bit pale, exhausted from sharing so much chakra moments after being born.
Naruto would begin wailing on the ground as if to say 'Hey! I exist too'
"Oh, Naruto!" Kushina scooped up Naruto, and looked round the village, it wasn't as bad as it could have been, but there was still heavy damage on the village, as they walked to the hospital, Minato would stay behind and help with looking for survivors, and clearing the rubble, Kushina continued to rush to the Konoha general hospital.