Just some preliminaries, I will be expanding on this when I catch time:
CHARACTERS – MAIN ANTAGONISTS
Abaddon
Story
Abbadon is attempting to merge human world with Hell (may or may not be same as the Demon World). This would result in humans being either killed or turned to demons en masse, and by the time story starts, he has managed to create multiple portals while preparing for the merge. Dante and Vergil are in Hell, attempting to stop him, but require help from human world's side to stop the portals.
Abaddon is the ruler of demons in Hell. He may not be killed, but only temporarily sealed.
Satan Claus
A demon masquerading as a Santa Claus. He normally utilizes a scoped hunting rifle. Aside from the rifle, he has 9 mm Luger as his secondary weapon, and may also throw hand grenades. On occasion he may utilize a flamethrower.
ENEMIES – BOSSESS
From here:
http://www.metaphysicspirit.com/books/The Lesser Key of Solomon - Goetia.pdf
Bael
A huge toad capable of turning invisible.
Marbas
A lion with diseased breath. Touching him physically, or with a non-electrified sword, causes ailments – reduced speed in particular.
Amon
A wolf with a serpent's tail. It is capable of breathing/spitting fire from mouth at long range. His tail is an actual serpent, and when it bites the enemy it causes continual health degradation for a limited amount of time.
Leraikha
An archer of human form.
Botis
A huge snake.
Marax
A great bull with a human face.
Naberius
Naberius takes a form of a black crane.
Glasya-Labolas
Glasya-Labolas is a winged black dog.
Marchosias
Marchosias appears in the form of a dog with gryphon's wings, serpent's tail, and ability to spit fire from mouth.
Stolas
Stolas is an oversized raven.
Malphas
Malphas appears as a crow.
Vine
Vine appears in form of a lion capable of spitting snakes.
Haagenti
Haagenti appears as a bull with gryphon's wings.
Amy
Amy appears in the form of flame (fire), and can thus only be hurt by Devil Trigger attacks.
Andras
Andras appears in the form of an angel with raven's head.
Haures
Haures appears like a flaming leopard.
Andrealphus
Andrealphus is a demon that looks like a peacock. He also summons peacocks and other birds as a form of attack.