Donovan is a Darkstalker hunter that uses his mythical blade, Dhylec, and a combination of telekinetic powers and summons. Donovan became a Darkstalker hunter to atone for his cursed blood. Along his travels he met Anita and allowed her to accompany him. At the end of Vampire Hunter, due to the numerous Darkstalkers he has slain, Donovan begins to lose control of his cursed blood. This in turn lifts Anita's "curse".
During Darkstalkers 3, Donovan no longer has a sense of self and in fact goes by the name of Dee. While he still has his sword and many of his powers, his fighting style is now more akin to a Darkstalker. His ending in Vampire: Darkstalkers Collection has him going against a grown Anita.