[ Elliot is at least able to keep up a cordial conversation. Forneus appreciates that. ]

Yes and no. Durin was corrupted by an Abyss curse, while Dvalin was tainted by proxy when they fought. The curse went into Durin's body and his blood. Dvalin ingested that blood when they fought, since dragons tend to fight with claws and teeth.

[ Biting and stuff like that. ]

The curse can be casted o a victim, or it can be spread via a medium, like Durin's cursed blood.