The Heart's of those with Black Blood are very vulnerable to Darkness, however they can never become Heartless. It acts as a powerful catalyst for the Darkness and allows those who possess it to control Darkness without any repercussions. One notable downside however is that those who carry Impure Black Blood go into berserk rages whenever it is active.
Shedo Dark has incredibly strong Black Blood, being a direct descendant of the Dark Emperor,
The Dark Emperor and his twelve Darkness, both in their original forms and in their following reincarnations, gain absolutely pure Black Blood when they fully awaken to their natures. This is largely due to the fact, that their heart has been fundamentally altered to Darkness, therefore it is pure darkness that runs in their veins.
- Dark Emperor (original progenitor)
- Dark Family (all powerful carriers)
- The idea for Black Blood and its side effect of insanity was taken from the manga Soul Eater.
- Black Blood also appears in TWBDL: Season One Chain of Dark Events written by Blaid. In it those with Black Blood have vampiric characteristics.