Who kills Ocelot?
Did either of them know venom wasn't the real Big Boss? Ocelot knew from the start because of the Hypnosis Therapy performed on you/Venom/Combat Doctor from GZ and himself to make you/himself THINK he's BB. Miller finds out after you complete the Truth Ending.
9/10 Ocelot Was In Love With Big Boss All Along While Snake Eater isn't exactly subtle about it, serving as a major part of Ocelot's development in Metal Gear Solid 3, it's a detail that's relegated to the subtext.
Ocelot was a good guy (in a sense) in mgs1, 2 and 4. He appeared to be your enemy but what he was really trying to do was dismantle Cypher. Even in MGS4 where he appears to be a moustache twirling villain, he's trying to destroy the Patriots AI and take control away from Cypher.