Vampire-like parasites who inhabit human hosts, the Ekimmu are not normal monsters.  The following is a template which can be placed over any existing creature, if that creature is possessed by an Ekimmu.  More on Ekimmu can be found in the Darkmatter book.

Ekimmu Template
Original Sized Aberration
Hit Dice: original hit dice in d10
Initiative: as normal
Speed: by size
AC: regular +2 (+2 natural)
Attacks: claws normal melee
Damage: claw 1d4 + Str modifier
Face/Reach: as original
Special Attacks: Drink Blood
Special Qualities: Rejuvenate
Saves: regular +2 for each
Abilities: Str +2, Dex +2 , Con +2, Int 16, Wis 15, Cha +2
Feats: original feats plus the Psychic(Suggest) and Psychic(Control Metabolism) feat
Skills: as original plus Concentrate and Suggest

Special Attacks:
Drink Blood: character can drink the blood of unresisting targets at the rate of 1 temporay point of Constitution per round

Special Qualities:
Rejuvenate: character may Concentrate DC 20 to heal 1 hit point each round.