The Beast of Darkness is a manifestation of all evil, rage and grief from Guts' inner self after Griffith's betrayal and the Eclipse event. From both events, Guts suffers dissosiative personality disorder where the Beast of Darkness inside him borns, and took over his mind as Guts wore the Berserker Armor for the first time.
The Beast of Darkness is aggressive, cold, cruel, and has an unsatiable battle lust. It also shown a bit manipulative, as it urges Guts to closer with his comrades so should he suffers their loss, it can took over his mind.
The Beast of Darkness bears some similarities with with Lord Vile;
- Both are manifestations of rage, hatred, and grief inside protagonist (Lord Vile for Skulduggery and the Beast of Darkness for Guts).
- Both are created as alternate personality of both heroes by respective main antagonist unintentionally (the Beast of Darkness indirectly by Griffith with the Eclipse and sacrificing the Band of Hawk and Lord Vile by Nefarian Serpine by slaughter Skulduggery's entire family).
- F inally, both try to take over the protagonist's mind should they wear their black armor (the Beast of Darkness has a bigger chance to take over Guts' mind when Guts dons the Berserker Armor while Lord Vile mainly took control of Skulduggery should he wear his armor again).