Hahadad is a dude call Joo Han.
Dragon Blood eventually drives its carriers insane as they try to consume Beast Blood in order to become True Dragons (TM) just like in the scene we had of Hahamom killing Wellman at their wedding in a former life.
Dragon Blood originated because the Seeker of Truth failed to become an Antagonist because his world was attacked too soon so in order to fight back (?) he injected himself with Beast blood, pretty likely from a C.O. called the Dragon - hence the name.
It cursed his family line and caused them all to carry each others burden and eventually grow insane. (Meanwhile Tiger blood is only carried by Wellman who gets reborn over and over again while Korean Goblin blood was for millenia only carried by Jisoo's dad who is immortal.)
Hahaman overcame the curse and the Dragon blood itself by accepting suffering as a part of life and living without regrets while also not looking for some way to cheat his fate or gain some grand power from the outside.
This caused him to lose his Dragon blood (which is probably why he didn't actually fight the Tiger despite having mastered Paramita: without Beast blood he can't harm it, only Jisoo and her dad could do that) but in return he got the life force of his ancestors - those who have honed their sword skills over generations by fighting the Tiger alongside Wellman and Jisoo's Dad.
So right now with Wellman having a holographic body and Hahaman overcoming the Dragon blood it looks like only Jisoo's Goblin blood remains.
Most of this is condensed in Man Chapter 7, Interlude #9.