FULL SPOILER ABOUT REGIS LIFE(Really ² Long spoiler)

Regis backstory is since he was young he was very strong and takes the Knight Commander’s title when he was young and all.

The emperor is very greedy and he wanted to use Regis...One time the emperor will ask him to share a drink with him, Regis was underage but couldn’t really refuse the emperor so they had a drink and when Regis was drunk the emperor will ask him for a favor and Regis just says yes because he can't refuse him and unknowingly when he said ‘yes’ he was actually swearing an oath that he couldn’t break unwillingly. When Regis found out it was too late...

The truth behind the oath was the emperor’s ring.with the permission of a side, they can’t disobey the owner of the ring.The ring only obeyed a person with the most mana, that’s why the emperor killed most of the magicians and wizards and collected their mana so he can be the person with most mana, that’s is the main reason that there no tower of magicians and there’s not much wizards.So the emperor got Regis’s permission when Regis was careless(when Regis drunk)and after that when he gave a order with the ring,Regis couldn’t disobey it.

Emperor used Regis to kill all his enemies and people he wanted to dead.
So later when Regis succeeded the Duke’s title from his father, he went in political marriage with our juvel(a nickname for juvellian)’s mother.... The mother’s name was Amelia...so after Juvel’s birth, Regis was busy most of the time and didn’t even come back home at the nights. because of that the mother, Amelia was depressed and thought Regis is cheating and doesn’t want her and they’re daughter anymore... which was not true at all, whenever Regis was home he played with Juvel and spoiled her(best daddy).... they were really sweet...there was actually a reason that regis wasn’t home most of the time at nights...The Floyen dukes(Regis family name) had some responsibility to check a sealed place from time to time, the first emperor of +100 years ago was sealed there(phanphil/immortal)....So regis will go to check to make sure that everything is sealed ... The other reason that regis wasn’t home often was because the emperor would use the ring on him and order him to kill enemies for him(shame on uu old mannnnn)...because of this Amelia thought regis cheating and they argues from time to time...Some times Regis would come after he was used by the ring, and amelia would sense that something is different about him... There is one time that emperor orders Regis to bring his weakness to him and Regis’s weakness is his daughter, Juvellian...
So his body moves on its own and he goes to the duchy to take juvellian to the emperor.....the emperor wanted to threaten Regis with his weakness...The emperor had some inferiority complexes and despised Regis... Amelia senses something strange and tells Juvellian to hide And when regis comes for juvel,amelia senses that there is something wrong with him and stops him and asks who he is, when they start arguing Juvel comes out from the place she was hiding and goes to call for servants to stop her fighting parents...but the servants ignore her and something seemed wrong(it's assassin's sent by current emperor)...when she goes back she sees her mother’s dead body and amelia’s last words were that she shouldn’t be scared.... she also sees Regis soaked with blood and some servants dead bodies there...and Regis starts crying very very very sadly and horribly(oh my daddy regis, anyway im single)....the small juvel thinks that her father killed her mother, and is horrified of him....on her mother’s funeral when juvel see Regis she immediately screams in fear and faints and after that this happened whenever she met him
(it's okay*hugging Regis)...Regis can’t bear hurting juvel so he go to phanphil( sealed emperor) and says that if phanphil can erases Juvellian’s memory with magic as in exchange he will open half of his seal...so just like that lah phanphil erases juvel’s memories and juvellian has no memories of her early childhood...Phanphil seal is not still completely open so he still can’t have a physical figure...after that Regis avoids Juvellian because he doesn’t want to hurt her like previously....but he always loved her and wanted her happiness(i love u regis(っ˘╭╮˘)っ)...the reason regis didn’t show up on her party in 1st timeline was because that day he was being controlled by the ring of the EMPEROR.....when Juvellian suddenly became lovers with Mikhail (the garbage ml original novel) the only reason Regis was nice to him and favored him was because he was juvel’s lover and he wanted her to be happy....when Juvel was accused of poisoning the princess, of course Regis without hesitation knew that she wouldn’t do such a thing and that the emperor sill use this chance to get rid of his daughter, so he took him to the prison because it was a safe place for her and even gave her one of his greatest swords that had magic which would protect her....after that he begged his disciple, the crown prince and the ML, Max to go and protect her daughter...he was always neutral to the succession of the throne and didn’t agree to rebel with the crown prince for the throne. but for sake of his daughter.. he promised max that he would rebel with him and help him in the succession of the throne if her saves his daughter....that’s the reason max visited juvel on the prison that day, but juvel who misunderstood everything killed herself...

after that Regis went crazy and killed everyone and destroyed in palace, the emperor tried to use the ring on him to stop him but because his mental state was crazy it didn’t work on regis and Regis killed himself too..its showed how Regis looked at the crown prince and said that it doesn’t mean anything if it’s Juvellian not here

when later juvellian remembered her memories, she understood that it wasn’t her father who killed her mother, but it was the servants that were actually assassins from the emperor.. that’s why they ignored her when she asked for their help......
so in current timelines, Regis gets a nightmare of the 1st timeline and remembers what happened then.
it was really sad that Juvellian had so many misunderstandings about him when he only wanted her happiness.
some sad stuff are that, Regis always thought about juvel and even referred to her by her nickname ‘juvel’ or ‘my juvel’ in his heart, he also stalked juvel sometimes.

the reason regis went to look for marriage candidates after hearing her type, was that he misunderstood that juvel wants marriage and Regis wanted her happiness so he was looking for best people...(please search stepmom candidates too)
so this time their relationship slowly will heals and juvel will get her memories(ﾉﾟ0ﾟ)ﾉ~