As I understand it, Ocelot grafted Liquid's arm to himself, and through the magic of nano machines (?), Liquid's consciousness manifested itself within Ocelot, effectively turning Ocelot into a body that Liquid's consciousness drives and uses as his own. This occurred after Liquid's "death" in the first MGS, amirite?

What would have happened if, say, Liquid's arm was surgically removed and grafted to a person while Liquid was still alive? For example, what if Liquid entered into a coma, had his arm surgically removed for genetic sampling purposes, and then had that arm grafted to another person? Would Liquid's consciousness manifest itself in the person to whom the arm was grafted?

*If* the answer to that last question is yes (a big if, which leads to the root question I'd like to ask), and if Liquid in this hypotehtical scenario would awaken from his coma, would that mean that there are 'two' versions of Liquid running around?

Do we know what happened to Big Boss' arm post surgical removal? Is it possible that in addition to the Les Enfants Terribles project, Big Boss' arm was grafted to another person?

@segajupiter: Ocelot used hypnotherapy to turn himself in Liquid Snake (speech patterns, mannerisms etc) so that the Patriots would think that Liquid Ocelot was Liquid, instead of Ocelot.

Since Liquid never had qualms with the patriots, he was not deemed a threat to them. This helped Ocelot to stay low, while he planned to use GW to seize control over the Patriots.

Liquid died at MGS1, after that it's all Ocelot.

Did you play MGS4? If not don't read but at the end big boss tells how Ocelot used hypnosis and nano machines to make himself adopt liquids personality, but nobody could ever become somebody else entirely.

@segajupiter: What the others said is accurate, Liquid died at Shadow Moses. The Liquid Ocelot personality was created by Ocelot to fool the Patriots. http://mgsdb.com/en/enc/492/3

We don't know if Big Boss' arm has any significance to the story yet, that remains to be seen.

Didn't Ocelot have the arm removed afterwards because it was messing with his mind when Snake was around? I figured the nanomachine and hypnotherapy stuff came after he already had it removed.

But if liquid died then why would the patriots be fooled by ocelot pretending to be liquid?

Theory a) the patriots are idiots who believe ghost stories

Theory b) its possible for liquid to have been in ocelot's body, so that's why the patriots were fooled by it even though that's not what actually happened. (Ocelot might have known it was possible also, or else why would he have attempted it)

Theory c) the patriots weren't fooled at all and simply let ocelot have his day in the sun, whether because they felt he was no threat to them or because he was unwittingly helping them in some way

@egg: theory d) mgs4's plot is an incoherent mess.

If you look at Ocelot's arm closely, you'l see it only resembles flesh from the forearm down, the rest of it looks like what Raiden is made of.

I feel as though Ocelot's parentage would have been enough of an explanation of why Liquid took over Ocelot.
Ocelot's father was The Sorrow, and though Ocelot may not have inherited his abilities, it may have left him with enough of a connection to the spiritual world to be open to being possessed by Liquid if his arm was transplanted on, especially considering the fact that Liquid would have made for one hell of a pissed ghost.

From the Metal Gear Wiki:

Big Boss later revealed to Snake that Liquid "possessing" Ocelot was a planned ruse in order to fool the Patriots as means of lowering The Patriots' guard against him. Big Boss elaborated that Ocelot was able to use hypnosis, drugs, psychotherapy and nanomachines to transplant the personality of Liquid Snake onto himself. Ocelot had removed the transplanted arm of Liquid Snake because the so-called "possessions" during the Manhattan Incident had caused an imbalance to his psyche.

By adopting the persona of Liquid onto his own, Ocelot was able to conduct the full scope of his plans while putting The Patriots into a false sense of security. Big Boss revealed that The Patriots assumed that the persona of Liquid Snake posed little threat to them, due to having dealt with Liquid Snake before during the Shadow Moses Incident. As such, they underestimated Ocelot and adopted a logic of repetition. The Patriots decidedly acted against him with minimal effort, in which Snake served as their main agent due to previously eliminating Liquid Snake in Shadow Moses.

This is what makes the most sense to me. However, only the first two sentences are backed up by in-game dialogue. The rest I assume to be inferred by the writer/editor/community, so it very well could not be true unless someone can find evidence to confirm or deny it. Then there's the issue of Liquid's voice coming out of Ocelot during MGS2. It very well could be that Kojima retconned it and originally it was a spiritual possession.

@marc: @voxus:

Ocelot getting Liquid's arm grafted onto his own and pretending to be Liquid happened between MGS1 and MGS2. All the therapy, drugs and nanomachines had some unfortunate side effects and he replaced Liquid's arm with a cybernetic one between MGS2 and MGS4.

Yeah, in 4 it's clearly a completely cybernetic arm. When he takes off his jacket it even pans up it, treating it as a big reveal. Who would have guessed that Dan wouldn't pick up on that.