Metal Gear Solid 4 family tree

Vamp
First appearance: Metal Gear Solid 2 (PS2)
Nationality: Romanian
Affiliation: Unknown
Looks like: Freddie Mercury
Voiced by: Phil LaMarr
Biography: A dangerous mercenary with a taste for blood, Vamp was a member of the Dead Cell unit that was co-opted to become the terrorist organization “The Sons of Liberty” in MGS2. Vamp seemingly has supernatural abilities, as well as being indestructible - Raiden apparently kills him several times in MGS2, though he is seen in the crowd at that game’s conclusion.
What he’s doing in MGS4: MGS4 will see a rematch between Raiden and Vamp - the 2007 E3 trailer showcases some of this epic fight, and it’s a doozy. Whose side is Vamp on though? We’re not sure yet…