"The magic words, Boss. I've been waiting nine years for 'em. “Kept you waiting, huh?” C'mon, say it for old times' sake..."
That mission still hurts―Even more so after the Truth tapes. He did everything he could to keep Diamond Dogs afloat, just so Big Boss would have a place to return to after he woke up. Kaz sacrificed everything for him, and what does he get in return? Betrayal. Ocelot betrays him, Huey betrays him... and even his closet compatriot decides that he isn't good enough anymore. All he has now is the phantom of a man who left him for dead.
