The way I see it, there are 3 realistic choices.
I could go for Snake/Liquid, Snake/Ocelot, or Snake/Big Boss.
I think Snake Big Boss would be best, but Big Boss/The Boss also has potential for awesome. Help me decide.
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Nominate Bahamut for the next Character Battle
http://images.wikia.com/finalfantasy/images/0/0e/Ffx-bahamut.jpg