A Flower That Couldn't Bloom
The war between the savages and humans ends with the savages capturing the Jeons, the only family of Welders in their land, which has taken up hunting in order to protect humans.
The savages execute the whole Jeon family, except for their youngest, Jungkook, who sees his parents die with his own twelve year old eyes.
The savages take custody of Jungkook as the only Welder in the land, trying fruitlessly to extract his Welding knowledge essential to all savage species.
Ten years later, a vampire coven applies for Jungkook's custody and gets it. The start is rough, and things keep on getting worse. Along the way the seven of them discover many things they don't understand. The only fact they're sure of is that their rabbit familiar has a weird fixation with the Jeon kid. Oh and that the Jeon kid isn't going to speak to them. Ever.
(This one writer is particularly bad at summaries, they tried to change it but they should accept that they're just bad at summaries).
OR:
OT6 are vampires, Jungkook is the son of the big bad hunters, there's so much blood between their species, and they don't like each other at all.