Solidus Snake

During his participation in the 1980s Liberian civil war, Solidus repeatedly kidnapped children caught in the battlefield, drilled them with combat training, and sent them out into the field as child soldiers. Among those children was Raiden.

In a manner of speaking, Solidus Snake was Raiden's adoptive father.

Arsenal Gear
Clone
Cursed Children of the Snake
Dead Cell
Emma Emmerich
George Sears
High-Frequency Blade
Katana
Laughing Octopus (MGS4)
Naked Snake
Ocelot
Olga Gurlukovich
Powered Suit
Raiden
Rosemary
S3 Project
Snake Arms (MGS4)
Solid Snake Simulation
Sons of Liberty
Sunny's Chickens (MGS4)
The Man in the Cardboard Box
Triple Crosser
VR Training