Dark Determination

"Johnny's eyes are the eyes of a killer. Johnny has the ability to discard anything... even his humanity."

The Dark Determination (漆黒の意志) is a phenomenon unique to the JoJo's Bizarre Adventure series

Description
The Dark Determination is a particular state of mind that reoccurs periodically in the series. It could be described as a character gaining some form of grim resolve, during which they have an unusual amount of resolve, notably the resolve to use deadly force. It manifests itself as small flames burning in the irises of the character.

The trigger for the dark determination depends on the individual. It could be that a loved one is in danger, as was the case with Jolyne Cujoh who heard her friend Ermes Costello being mugged by prison guards, or Josuke Higashikata seeing that Yasuho Hirose, his love interest, being kidnapped by an enemy. However, the dark determination will trigger with any sufficient will. For instance, Johnny Joestar's dark determination was centered around his goal of obtaining the Saint's Corpse.