[POV: 3rd Person]
[Scene: The Pure Lands]
[Track Change: Undertale 'The Choice']
Anthony thought of something, something risky, preventing the Nine-Tails Rampage on the night of Naruto's birth, he didn't even know if he would show up in time, so he worded his request differently, so that even if he was late and the worst had occurred, he could do damage control.
"Grandfather Hagoromo, if the goal of this Zetsu is to gather the Tailed Beasts is there a way you can help us suppress the Tailed Beast enough to listen to us or prevent them from being taken? Like a seal or a way to connect spiritually and have them know you sent us?"
Hagoromo thought this was reasonable, after all the tailed beasts were also his children, and if his children and grandchildren could work together, it would be harder for Zetsu to accomplish his goal.
"I can transfer some of my experiences with sealing techniques, you don't need to worry about identification for the Tailed Beasts though, you will be taking my Chakra, and I will be building your Chakra network, you will have the same Chakra signature as I do. I know there are some Tailed Beasts sealed in Humans called Jinchuriki, the sealing technique I will give you will take the burden off the Human's Chakra network, while also giving the tailed beasts vision and hearing of the world around them. I care a lot for my children you see."
This was better than Anthony could have asked for, sealing knowledge, editing sealing formulae, a way to reliably speak to the tailed beasts, an easy time for Naruto's early training, and even the possibility of stopping the Nine-Tails rampage were enough benefit for him. Asriel was a bit confused, but he didn't doubt Anthony or thought he would do anything to harm him, they were going to be sharing a body soon anyways.
Both Asriel and Anthony agreed to Hagoromo's offer, who was very pleased.
[Track Change: Undertale 'Undertale'] (A/N: Duh.)
'There it is again.' Hagoromo thought, before bluntly asking.
"Young ones, are either of you causing music to play right now?"
Both Asriel and Anthony looked at each other, and both replied,
"It's Asriel. (It's Me.)"
"How and what causes it?"
Asriel replied, "It is caused by our Magic, it reflects our mind and SOUL. Depending on circumstances, locations, and the emotional state of the Monster, a theme will be played. If we are content, a smooth melody, being scared plays an eerie theme, if we are in battle a tense theme plays, Anthony could do this too, but he has never used Magic before, this doesn't change much though."
Hagoromo stroked his goatee murmuring about wanting his own theme music.
After the small tangent Anthony and Asriel were getting ready to become a guardian. Anthony through a bit of trial and error managed to summon his SOUL outside his ghostly body and handed it to Asriel. Asriel with help from Hagoromo, absorbed Anthony's SOUL, while Hagoromo ensured Anthony's consciousness was preserved.
Meanwhile Asriel started to change, first he started to grow, reaching a height of 6ft 4in or 193cm, second black markings appear on the sides of his face, third on his back are black nine magatama similar to the marks on his face, fourth his SOUL appears on its own with his White upside-down heart shaped SOUL inside of a right-side up Dark Blue and Purple SOUL, looking closer you can see a faint Red glow come off it.
His new SOUL returns back to his body and Asriel opens his eyes, the last changes occur, his eye are now two different colors, his right Red and left Green, and as the last changes to Asriel's Chakra network a made, his horns sprout, one a white brighter than light, the other darker than shadow. Hagoromo gave him a new robe and now, Asriel was now ready to be a guardian.