On a certain hill in the underworld a blue circle with a rams head in the middle appeared followed by a middle aged man with shoulder length black stepping out.
Glancing at his surroundings the man started off down the hill to the estate below owned by the Gremory family, as he walked a baby began to cry " shh Takashi " whispered the man " I'm taking you to a family that can raise you in a safe environment far from the dangers I have brought upon you ".
A single tear fell from the man's eye it was all he could shed for his son that he would never see again. When he reached the mansions gates he set the baby down conjuring a magic circle on his finger, blue flames appeared and wrapped around the baby's crying form sealing his powers that he had inherited next the man pulled out a ornate katana laying it beside the boy he whisper " This is all i can give you its the only Desecration gear in existence my last project inside contains the spirit of leviathan's only daughter treat her well and knowing how much you look like your mother I'm sure one day you can release her spirit". With that he placed a note on the body flared his massive aura and teleported away.

View change
Responding to the Immense aura a man in his early twenties with shoulder length crimson hair bolted from bed and sprinted outside red black flames of destruction pouring out of him fearing the worst , upon reaching the gates he spotted a newborn child and katana he knew all to well.
The young man threw open the gates and pulled the child into his arms, picking up the sword and pocketing the note dreading what was written inside he walked back into his fathers home.
Striding silently into his sisters nursery he placed the baby boy in the crib next to his sister smiling at the two he kissed both there foreheads and left the room.
Entering the hall outside the nursery he came to a start to see a beautiful young woman with silver hair in night wear with a worried expression " whats wrong Sirzechs" she asked " nothing Grayfia " responded, the young man now know as Sirzechs " it just seems whe have a new addition to the family " handing her the jewelled sword "please put that in your shadow dimension I have one thing left to check and I'm dreading the answear to this question" he explained with a sigh suddenly a crimson circle appeared beneath him and he disappeared.
Looking a the sword her husband handed her Grayfia let out a gasp recognizing the sword and the spirit inside, praying she was wrong she opened a portal put the sword inside and went back to bed.

View Change
Now in his office Sirzechs unpocketed the note and opened it blue little caressed the room as the figure of a man appeared " hello Sirzechs as you now know that boy is my son Takashi, he's half human but was still born as a pure-breed devil due to my power I have sealed his power of the Blue flames of hell but they will one day be released".
Taking a pause the hologram shed another tear " I ask that you raise him for me I know its unfair to ask this knowing what damages he could cause in the future, but he's all I have left I have left him my last creation the Desecration gear Abyss its on par with the true longinus".
" I no longer have the power to protect him my fight with god has left me weak and I need to rest , I leave the underworld to you and the four new maous but know this if harm befalls my son I will tear the underworld asunder during my grieving and with this goodbye my friend raise him well".
The note burst into blue flames and was gone falling back into his chair sirzechs let out a sigh then began to laugh
"HAHAHAHAHAhahahaha ok old geezer ill raise your son, but haha to think you would finally have one psst how long did it take and with a human no less you definitely are a strange Satan-sama be at peace your son is safe.