One common theme is the struggle between light and dark within the characters. The Digidestined of Darkness often face internal conflicts as they navigate their role in a world that typically favors the light. Another theme could be redemption. They might strive to break free from the expectations associated with being of 'darkness' and find a path towards goodness.
Power and its corrupting influence are also common themes. In Digidestined of Darkness fanfiction, the characters might initially be drawn to the power that comes with the 'dark side' but then realize the negative consequences. There can also be a theme of isolation, as they may be ostracized from the more 'light - sided' Digidestined, which then leads to their own unique journey of self - discovery.