"When I said I could help you, it meant that I could help you strengthen your soul and teach you how to manipulate it. Whatever you do next, it'll be entirely up to you. Whether you'll succeed or destroy yourself in your attempt to seek power, it'll all be on you."
Without any hesitation, Serafall nodded, "Please help me."
"Have you taken the candy I gave you earlier?"
"Yes."
Kisuke then stood up and took out his cane while saying, "Stay still. This is going to be uncomfortable so you have to bear it. I'll also transmit basic Soul Power manipulation techniques to you so make use of that to ease the pain."
Serafall was instantly taken aback, "P-pain? What pain? I hate pain."
Truthfully, Kisuke can't strengthen the soul without doing it artificially, and going that way would only make him like Mayuri. Nevertheless, he didn't technically lie to Serafall.
From the start, she already has developed a strong soul through her experiences and long life. It is just that her Reiatsu was currently running dormant. By sending his own Reiatsu directly into her soul, it would immediately jump-start the circulation of her Reiatsu, essentially, making her soul 'stronger'.
"Please don't resist in any way and allow me to send a strand of my energy into you. If you were to resist, even unconsciously, this will fail."
After getting a nervous nod from Serafall, Kisuke's playful grin immediately morphed into a devilish one as he pointed the tip of his cane at her forehead, "Then grit your teeth~!"
Serafall's nervousness peaked as she unconsciously backed away from the sinister figure, "W-wait... What are you going to do? Let me pre--!!!"
Kisuke didn't let her finish her words and struck her forehead to transfer a massive amount of his own Reiatsu to her. Serafall's soul, which hasn't ever experienced any direct interference, jolted into action, resulting in a pain that she had never felt before.
"Ghhh...!!! Ahhh...!!!" Serafall tried to contain her scream of agony but the torment was directly coming from her soul. Even if her body was used to physical pain, an intangible thing like her soul wasn't.
While hugging herself and wheezing, she heard Kisuke's unforgiving voice, "I also transferred to you the necessary technique. Use it and the pain should subside after a few hours."
She wanted to say something back, but Kisuke just waved his hand and she was teleported away just like Sona, but in the opposite direction, "Now then... It's time to wait. If I get it right, Sona-chan would be the first one who'll achieve it. However, there's still the danger of that Hollow Factor and it should be coming into life once more before that."
.
.
.
The moment Sona was teleported away, She couldn't help but smile wryly at how Kisuke does things, 'As abrupt as ever.'
To combat the rays of the sun that would slowly kill any normal to decent children that received the Deities' blessing, Sona created a barrier around herself and thought about what she should do from now.
'Kisuke gave way too much attention to that useless water ball, so I guess it's safe to assume that I should go that path? But how can I improve it? And what was that strange reaction Nee-sama had to it?'
Taking a deep breath, Sona tried conjuring it once again to examine it further and figure out why Serafall reacted that way, but due to the enormous amount of concentration needed for it, she had no choice but to disable her barrier.
Although she was successful in making it appear once again, she could only observe it for around ten minutes before she had to dispel it and erect her barrier once more.
'Staying unprotected in this environment is way harder than I initially thought. I didn't know a massive amount of stagnant Magic Power in the area could compound the heat like this.', thought Sona as she tried to clean off the sand that stuck to her skin. She couldn't even sweat properly as it would evaporate instantly.
Sona then tried conjuring water through her normal Magic to herself off, however, she found it extremely hard to do so, 'Is the atmosphere too dry, since I can't conjure much?' It was at this point that it finally hit her, "!? Wait... If I can't gather much water in this kind of environment, how come I don't have the same problem when I'm summoning that water ball? I should have noticed it if that's the case."
Instead of Water Magic, Sona opted for taking out the heat from the air around her to cool herself. After being sufficiently refreshed, she went back to what she had been doing before and summoned the strange ball of water once again.
This time, she used all the mental power she had left to observe and examine the ball, completely discarding her awareness of her surroundings.
Directly behind her was Kisuke, who was silently watching her progress. Normally she would have already noticed him since he wasn't even trying to hide his presence but she was so focused on her task that he wholly eluded her, 'She's doing great. Though I need to make sure that she doesn't completely forget about her body's state.'
The main reason why Kisuke wanted a harsh desert for their training ground was mainly for Sona. It is not just so she could realize what's strange about her Magic, but this kind of environment would help her push past her limits and would also allow her to control her newfound power much faster.
Serafall, on the other hand, didn't need it at all as she's already capable of understanding things at much deeper levels thanks to her experience and profound understanding of Magic. Kisuke thought that just by putting the two of them together it would have a positive effect on both of them.
'Now then... I wonder how Sera-chan is faring.', leaving silently, Kisuke arrived a few hundred meters away from Serafall and saw her sitting on the sand while clutching her head. This time, however, she'd already stopped her screams of agony and she was just closing her eyes with an expression that she was enduring something, 'She's doing it much faster than I thought. As expected, these sisters are geniuses.'
The next three days, the sisters progressed quickly, more than Kisuke had expected. Sona was already able to use her Soul Power and Demonic Power simultaneously and skillfully, leading her to reduce the energy consumption of her strange 'water' greatly and even manipulate it into different shapes with ease.
Serafall, meanwhile, had already got ahold of her Soul Power and started controlling it skillfully too. After a few tries, she was now able to see the door of what she was trying to achieve on the horizon and became enthusiastic about her training, to the point that she never stopped moving. Thankfully, her body had already been nourished by Ki for a long period of time and allowed her to resist the harsh environment without it affecting her.
At twilight, Kisuke decided to fetch the two for them to rest. Until an incident happened.
Sona went berserk and the Magic Power within the whole region started gathering to her spot uncontrollably.
Editors:
28th00: When in doubt, Hollow it up! It usually does something weird! Considering devils are creatures of Sin, and Hollows are revenants of Instinct, they actually have really good compatibility… And act like a Dragon Rampaging(which is the scariest power up in DxD pretty much, and all dragons have it, it lets them punch up by a few orders of magnitude in a blind rage of pure power), but hungry I assume? Hollows are hollow for a reason...