Sorceress Edea is the sorceress of the present. Sorceress Adel is the sorceress of the past. Sorceress Ultimecia is the sorceress of the future who is trying to combine the power of all three in order to reign supreme. She will enslave the human race (for reasons too massive to elaborate on). The Sorceresses are the shadow archetypes (particularly Edea, as she is the one with whom the audience becomes familiar). Sorceress powers must inhabit the body of a girl. Sorceress Edea used to be the Matron of orphan Squall. Sorceress Edea specifically despises Squall, the hero and leader of the anti-sorceress movement.
Sorceress Edea has many symbols associated with her. Most obvious is her occult appearance, involving dark colors and castles. In addition, the creepy music filled with chants sung in Latin that plays when she is shown help to strengthen the association of evil with the sorceress.
The Sorceresses can be compared to the Devil in "The Devil and Tom Walker" because they both fulfill the devil/shadow figure archetype. Both are the primary cause of the hero's downfall, and both have symbols of darkness and hell associated with them.
His face was neither black nor copper-color, but swarthy and dingy, and begrimed with soot, as if he had been accustomed to toil among the fires and gorges.