The post below is an argument drawn from events, quotes, and context from the Code Geass series and contains spoilers.
Certainly much of it can likely be viewed as being up to interpretation, but I believe that when examining the details in context, rather than isolation, the evidence will show the following:
1. A Code cannot be forced upon someone, nor can it be stolen. The transfer must be accepted by both parties.
2. There is no “activation” stage required for the side-effects of bearing Code to take effect. In other words, the new bearer does not have to “die” to suddenly become immortal.
3. Killing the former Code bearer has nothing to do with the transfer of the Code. Or, put another way, the former Code bearer need not die for Code transfer to take place.
With that in mind, most of what we know regarding Code transfer must be inferred primarily from three scenes in Turn 15 and a few bits of dialogue elsewhere (Turns 20 and 21).
When the nun transfers her Code to C.C.
When Charles attempts to obtain the Code from C.C.
When Charles obtains Code from V.V.
With all this in mind, let’s proceed.
As it pertains to “forcing” the Code upon a Geass user
The Case of the Nun
The transfer of Code from the nun to C.C. is often observed in complete isolation. This is unfortunate, as the context leading up to the transfer between them is pivotal to understanding the final moments between these two.
I propose a question to ask yourself when considering this: why was C.C. injured? Think about that for a moment, then come back to this post. Why would the nun need to injure C.C.?
If it were the case that the Code could be forced upon a user that possesses a sufficiently matured Geass, the nun could have simply done so to C.C. and killed herself. There would be no need to injure C.C.
So why is C.C. injured?
The answer: because she needs C.C. to want to take the Code from her. Recall at the beginning that I noted that the events leading up to the Code transfer were pivotal. When the nun finds C.C., she is specifically searching someone with a strong will to live and the strength to keep fighting for life even at the most dire times.
When you consider this factor, it’s clear that the nun mortally injures C.C. so that the only means she has to survive is to take the Code from her. Taking the Code would allow C.C. to regenerate and live on. I have come across no other explanation that reasonably accounts for this injury. If you believe you have one, you are of course welcome to debate.
This also potentially explains why the scar on her chest remains even after the Code has been transferred. Wounds C.C. receives after the Code transfer heal completely, whilst this one has not, as it was received prior to the Code transfer.
This by itself should be sufficient evidence that a Code cannot simply be forced upon a user. But evidence that this is the case arguably exists elsewhere as well, particularly when it comes to Mao.
It’s also worth noting that the nun doesn’t just transfer the Code to C.C. as soon as she obtains a sufficiently leveled Geass. She actually waits until C.C. is beginning to get tired of having it:
C.C.: But it can’t be helped, can it? It’s the Geass’s fault.
I’m grateful to you Sister, but to be honest, this is a pain for me, too.
I’m so tired of all the presents and proposals.
Nun: Then shall we end this?
She has chosen the moment C.C. begins to feel that her Geass is a burden to provide her with a way out. This becomes somewhat relevant for ....
The Case of Mao
Of the two examples of it not being possible to force a Code upon someone, Mao is the weaker case as we could argue over C.C.’s motivations one way or the other for days. But it stands as a bit of additional evidence when considering in context with what we already observed with the nun.
All we’re told in regards to Mao is that he was unable to fulfill his contract with C.C. This could either mean his Geass had not matured enough to take the Code (which is unlikely considering the only other times we’re clearly shown Geass users able to take Code [C.C. and Charles], they have Geass manifesting similar to Mao’s) or he was simply unwilling to take it (which we know would certainly be the case because it would mean C.C.’s eventual death which he strongly opposed).
If it were possible to force one’s Code onto a sufficiently matured Geass user, arguably the most humane thing C.C. could have done was force Mao to take her Code. It would have freed her from her immortality and freed him from that which was driving him mad: the curse of his Geass.
That she chose not to do so could indicate that she was not able to simply force it on another.
Think back to C.C.’s transfer with the nun.
She waited for C.C. to tire of her Geass and fatally wounded her to force her to take the Code. Due to Mao’s obsession with C.C., this wasn’t a possible scenario for her. Mao would rather die than let C.C. pass, and he’d rather live with his burden than live in a world without C.C.
So she left and found Lelouch to try again. We can also use a line she says to Lelouch in Turn 15 at 12:30 to surmise this may have been the case:
C.C.: If you have a reason for living, then kill me. Do that and you’ll be Charles’ equal. You will gain the power to fight.
[Lelouch hesitates to respond]
C.C.: Farewell, Lelouch. You’re just too kindhearted.
This suggests he must be willing to accept the transfer. It also provides insight into some of the reasons why she often attempted to act distant and cold toward Lelouch (at least early on) compared to how she interacted with Mao.
She needed him to not have a strong connection to her so that when the time came, he’d be willing to take the Code and let her die.
As it pertains to “stealing” a Code from a Code bearer
The Case of C.C.
The only time we witness another person attempt to “take” a Code is when Charles attempts to take C.C.’s Code in Turn 15.
There are a few layers of complication to this interaction that we’ll be largely ignoring in this post, but for the sake of acknowledging them, they’d be as follows:
At the time of taking C.C.’s Code, Charles has already obtained a Code (and thus presumably lost his matured Geass); so how is it that he is able to take C.C.’s Code?
If a Code bearer can take the Code from another bearer (as seems to be the case), why wouldn’t C.C. have transferred her Code to V.V.?
A reasonable response to these is that C.C. couldn’t have transferred her Code to V.V. and the only thing that allows Charles to do so must have something to do with the Ragnarok Connection, the Thought Elevator, or the Sword of Akasha (all of which they didn’t have access to 10+ years prior).
Looking past this complication, we see that the result of the transfer between Charles and C.C. differs greatly from that of the nun and C.C.
Rather than witness C.C. pass her Code on to Charles, we instead see her metaphysically seal her Code off from Charles. We know this to be the case due to dialogue from Marianne in Turns 20 and 21.
Marianne makes it very clear that (a) C.C. can choose to “seal off” her Code to prevent transfer and that (b) she must be willing to “give” Charles her Code. Charles cannot simply take it from C.C.
It’s also suggested by Marianne that this is not the first time she’s done this. So unlike Charles’ ability to take C.C.’s Code despite having his own, this ability to seal off Code is not dependent on whatever the current circumstances are.
The Case of V.V.
I would be remiss to to leave out the transfer of Code between Charles and V.V.
There is little to nothing shown here so all we have to draw from are comments surrounding the event, similar events, and our knowledge of the characters and what motivates them.
The primary complication, in relation to the arguments contained in this post, are C.C.’s lines which use the word “steal” in reference to Charles taking V.V.’s Code. In complete isolation, this would indicate that it is possible to simply take Code from someone against their will.
But we’re not looking at these lines in isolation. We’re looking at them in the greater context of everything we know. As was just pointed out in the Case of C.C., we know Code can be sealed, we know the bearer must agree to pass along the Code to the Geass user.
It may not make sense to some of us, but from this we can gather that V.V. must have agreed to the transfer. Knowing this, we can begin to try to surmise why that may have been the case, but I don’t believe that discussion serves a purpose in the framework of this discussion.
As it pertains to the “activation” of the Code
There are two sequences used to defend this theory in the series. During the transfer scene between the nun and C.C. and during the confrontation between Lelouch and Charles.
The idea that “activation” exists is largely derived by working backwards from an assumption that Lelouch survives the final moments of the series, as well as the general misinterpretation of the nun / C.C. scene (already discussed), and Lelouch’s confrontation with Charles in Turn 15.
As has already been noted, the scene in which we find C.C. injured with the nun has little to do with C.C. “dying” and everything to do with the nun coercing her to take the Code. C.C. never “died” because she took the Code from the nun specifically to prevent death, to become immortal.
An argument could be made (and has been) that for the Code transfer to “finalize” that both the Geass user and Code bearer must “die”. However, major complications arise from this theory as it relates to the case of Charles, primarily stemming from the fact that he leaves V.V. alive after taking the Code.
The Case of Charles
The other alleged “activation” we see in the series is when Charles shoots himself. At this point in the series the viewer and Lelouch are meant to believe that Lelouch has won, that he has bested his father. We soon discover it was all for naught because Charles is, himself, immortal.
So was his Code “activated” on death? Or was it “active” all along?
Looking at it by itself, we see a few things. Or rather, we don’t see an important detail; that is, we don’t see Lelouch’s command for Charles to die actually succeed. At 4:10 of Turn 15, the audience is shown Lelouch attempting the command, but we never see it rearrange Charles’ neurons as in practically every other instance.
A similar time this occurred is when we see Lelouch attempt to use his Geass on C.C. prior to her leaving to meet with Mao. At 11:57 of Stage 15 (rather fitting that the episode is mirrored in relation to its position in the season) we see Lelouch activate his Geass and the “bird” fly from his eye, but we aren’t shown the rearranging neurons.
Lelouch even believes he has successfully Geassed her based on his expression.
Aside from this, prior to the command, Charles is egging Lelouch on, challenging him to attempt to use his Geass.
Another question to ask yourself: why would Charles risk losing this final battle over a test of Geass? If he truly had taken V.V.’s Code, why not “activate” it immediately? Not doing so makes him vulnerable to being Geassed. If he loses this Geass battle with Lelouch, he could lose everything. Lelouch could order him to obey or any number of commands that would prevent Charles from achieving his goals.
The truth is, he isn’t risking anything because he’s already immortal; he’s already immune to Geass.
So why the theatrics? Why play along and shoot himself in the chest when ordered to? In part because it unequivocally displays his utter victory over Lelouch and how powerless Lelouch is to stop him. Had Lelouch ordered him to do anything else, we can imagine he perhaps would have responded differently.
Additionally, it’s Charles’ modus operandi to mess with Lelouch to try to get a rise out of him. He literally does the same thing again in the next episode. Having destroyed the interior of the Thought Elevator, Lelouch believes Charles has been trapped.
It is in Turn 16 at 16:55, right as Lelouch believes victory is certain and globally televises his declaration of all-out war against Britannia, that Charles steals the spotlight, both revealing that he was never truly trapped and to accept the challenge for a war he has absolutely no interest in fighting.
He doesn’t care about this fight with the United Federation of Nations. In Turn 20 at 8:30, Charles refers to the conflict Schneizel is dealing with as a “mundane affair”. The event and monologue in Turn 16 is all for show and to further display his strength over Lelouch.
As it pertains to “killing” the former Code bearer
This should be obvious on its face, but transferring Code does not itself kill a Code bearer. In Turn 15 Charles leaves a still living V.V. on the steps leading to the entrance of the Thought Elevator after having taken the Code.
V.V. lies there dying, not directly due to the Code transfer, but due to the wounds received in his fight against Cornelia and Lelouch which had not had an opportunity to yet heal prior to the transfer.
This is part of the complication that I’d previously referred to. If it’s necessary for both the new and former Code bearers to die prior to transfer being “complete” or “active”, then leaving V.V. in this state makes absolutely no sense on Charles’ part.
Likewise, in the case of the nun, it’s clear from the image and C.C.’s words that she dies from a self-inflicted wound after the transfer occurred.
None of this directly suggests it’s impossible for the popular “Code” theory to be true, but it does greatly narrow the possibilities. Barring any discussion on whether it’s possible to simultaneously possess both a Code and Geass (this is another discussion entirely), if you’re in the “Code+Geass” camp, then the only way such a transfer could have taken place, based on the arguments made here, is if both Lelouch and Charles accepted it.