Question about Ocelot.

Hi, well, first of all I should say that I've played MGS 1,2,3,4. A few times. I also should say that MGS has the most complex storyline in a videogame I've ever played. Maybe that's why I love it so much :D But I just don't get it.

Ocelot is the son of The Boss and The Sorrow. He was a XX- Agent. ( did spy for many,many organizasions at the same time.) Was raised by the philosophers and worked for them. Later He and Zero created the Patriots. and bla,bla,bla

The thing that confuses me is in MGS4. Where Big Boss said that he was an ally the whole time, from 1972. And the thing with his arm " Trick the Nanomachines " I know that he pick up Liquids arm. But then refuse it and changed it again by another " normal " arm.

I'm just so damn confused. Ocelot is one of my favorite charakters of MGS ( after Big Boss, Solid, and mgs4Raiden) ;D but I am not understanding a fuck about him xDD

could someone explain pls? xD Is he a good boy or a badass motherfucker ::D:D:D