Bloodline Extermination.
Something I got from Okhwang as he was talking about his own Universe, Ancient Dao Universe, and various Universes where cultivation existed, that of the Okhwang's and similar.
Cultivator Clans and Sects would often annihilate everyone for even the slightest amount of offense. People there really had a very high amount of pride, arrogance, and pettiness, and god knows nothing else.
In the end, even though I usually kept it very well hidden, I also had a fair amount of arrogance and pettiness inside me, but I knew how to control and mask it perfectly.
Soon after, I returned from my thoughts to the realspace and activated the extraction ritual.
Magic Circles behind Issei's tortured and beaten body activated as he started shrieking in pain because it was tearing his soul apart. After several minutes he shrieked of pain quieted down, as blood flooded his mouth and he could even scream properly, and his eyes exploded from the enormous amount of pain.
If not for several spells I have cast before on him, he would die, but alas, in my sadistic nature, I wanted to torture him even more.
Afterward, I cathed a ball of light that flew out of his body when the ritual was done.
"Finally."
As I looked at Issei's body that was changed to beyond anything before, I have muttered... probably even Hela would be proud of me to torture someone to such an extent.
I stretched my hand and cast a particular spell that trapped escaping soul of Issei Hyoudou.
"Even if the chances for your reincarnation are almost zero, but alas, as Son of Destiny of Draconic Deus, it still exists, and I prefer to cut down all loose ends."
I released Energy of the Fateless One that invaded the soul of Issei Hyoudou and started devouring it like a mad until the entire soul was devoured by the Energy of the Fateless One, which then subsequently returned back to my body.
When it returned, I found out that my Demonic Energy Reserves had increased tremendously, reaching almost 700 Units, and even my physique was strengthened by a significant amount.
"Who would have thought that from absorbing the soul of Son of Destiny, I would benefit greatly."
Son of Destiny could be called a protagonist of the word.
The World itself would bend World Laws to help him get stronger, give him fortuitous encounters and basically give him the easy road to power. Usually, people like this would get stronger at an unprecedented rate that opposed all common sense; they are almost impossible to kill once they fully awaken to the Son of Destiny. So basically, they were enormous pain in the ass, like cockroaches.
But in the end, there exists no free lunch.
Son of Destiny was created only for one purpose.
When the World itself felt immense danger from something that could lead to the destruction of the World, it would create a Son of Destiny.
In this case, the danger should be Evies that wanted to invade Draconic Deus, but it then probably shifted to Chthonian Empire that wanted to tear down Dimensional Gap.
Fortunately, Issei Hyoudou didn't ever fully awaken as Son of Destiny, only half-awakened, because the majority of the Son of Destiny Power was dormant and waiting to be awakened. If my guess was to be correct, he would fully awaken as one only when he managed to awake Boosted Gear.
Then he would truly become Son of Destiny of DxD or aka Protagonist of the Word.
Fortunately, he was dead; not even his soul remained.
I conjured a massive amount of Holy Flame as I burned down his abomination of the body till not even dust remained.
I then only stared at the environment of Kuoh Town as I was thinking about something.
"Are you okey, father?"
Asked Sirzechs, who returned to my side.
"Yes... did you know that that guy was Son of Destiny of Draconic Deus?"
I asked as I pointed at the place where the body of Issei Hyoudou was before I destroyed it.
"Really?"
This revelation shocked Sirzechs because he knew what that title represented and the power that came from it.
"Indeed... Rias earned great merit with this, as I think this Son of Destiny was created to destroy Chthonian Empire because of our plans."
I said to Sirzechs as he nodded in agreement.
"I never thought that Rias would mature so quickly."
Muttered Sirzechs.
Because he was the eldest of all siblings, he wanted for all of them to get along well, but in the end, he had his duties, and he wasn't extra close to the younger ones as much as he was to Sigmar or Hildegarde.
While Sigurn and Renxue were more close to him than Rias, even though they shared the same mother, alas, Sirzechs spent most of his time training and fighting or ruling. Sigurn and Renxue were eager to learn from their eldest brother. At the same time, Rias was more interested in lazying around than training.
"Dire circumstances are the best teacher under all of the Heavens."
I answered him with one sentence.
"Come, I need to talk with Rias and Vali."
I said shortly after, as we have left Custodians to do their job.