Regis Nex is the king of Chaos. He has deep affection towards the demon clan's Serin. However, due to some circumstances, he imprisoned her for betraying him. It is still unknown who his son is but it is said that he has only one son. He also has a daughter with Iffrita Noah, Miya.
Regis Nex has brown hair and wears royal clothes with a cape. His clothes usually have fur. He can adjust his clothes with magic. When in battle he has his sword Depore and usually takes off his cape.
When Regis Nex was young he would help everyone in need. He was kind and very protective of his comrades, especially Serin. However, now Nex has changed completely. He is cruel and merciless towards other people. This could be the result from Serin betraying him and then running away with his child. Also, having lost his brother to Caladbolg, he has experienced great pain.
It is then reveal that his cruelty sprouted after a conversation with Caladbolg. Seeing the demon slaugther his men and innoccent civilians horrifyied him, showing that he did care for people. After the talk, he resolves to kill the latter even when goaded at the possibility of his brother regaining control.
Another aspect is that he vehemently denies any relation with the Night Clan. This could be hinted to his reminding of how he became the king, or because of the secretfear he has of being Night ie human due to whatever Calabolg touches mutate beyod recognition and purpose everything in Chaos, Everything except him and his bloodline, due to him being night, human before, making his children human-demon and human-dragon hybrids.
- "You're still the same. Your body's being tortured, your mind being eaten by nightmares... It's a punishment worse than death... The traitor of Chaos. The one who betrayed me. Ironic, don't you think? If you aren't alive, I also can't go on living. As long as I need your blood. You are mine. A piece of bone, a drop of blood, all of it. I'll never let it go. Serin." - Regis Nex to Serin, in Chapter 5.
- "Claiming to be my son, and even running away, I can tolerate them. However! Rebelling against me... I will not forgive. Go ahead and vanish along with those you care about." - Regis Nex to Xix, in Chapter 45.
- "If there's a life I can save, if that someone desires my help, I will not stand idle while that life vanishes right in front of me. That's my sense of justice." - Jae-Hyuk, Ch. 34
- His original name was Chae Jae-Hyuk before Serin named him Demon Nexus Nex.
- His sword is Depore Magnasetia.