In the end, when Lelouch is about to die, Nunally holds his hands and is able to see his memories. How? The theory that Lelouch is immortal explains this, but that isn't official.
Is there any official explanation for this?
In the end, when Lelouch is about to die, Nunally holds his hands and is able to see his memories. How? The theory that Lelouch is immortal explains this, but that isn't official.
Is there any official explanation for this?
First of all. Nunnally most likely did not see Lelouch memories.
One of the abilities Nunnaly has is her extreme perceptiveness and intelligence
Nunnally has shown to be not only perceptive, but also intelligent by coming up with a similar plan as Lelouch (using the Damocles as an object of hatred). source
With this information given and the fact she had a similar plan to begin with she might have seen through Lelouch motives the moment he fell down right next to her
being taken to witness the execution of the U.F.N. leaders. When Suzaku, in the guise of Zero, appears and impales Lelouch on his sword, Nunnally can only watch in shock. When Lelouch falls near her, she takes his hand and realizes that he has sacrificed himself on purpose
Therefore it is more plausible that Nunnally grasped Lelouch's intentions at the moment of his death, instead of finding out what actually happened through a direct memory transfer.
I am not that sure if there is any official explanation about this. But from what I understand and have answered here,
Lelouch got his dad's code. He beckoned the World of C to lend him its powers, and he took Charles's code before Charles passed on. The reason why Lelouch still has his Geass is because he didn't take the Code from the same person who gave him his Geass: he took his Geass from CC, and he took his Code from Charles. Thus, he now possesses both immortality and a Geass.
To further corroborate this, however, remember that when Nunnally held Lelouch's hand he transferred his memories to her. CC also did it when Lelouch touched her accidentally back then, so it could be assumed that people with Codes are indeliberate telepaths. This leaves us with both immortals traversing the world for the rest of eternity.
Nunnally did NOT see any memories or code visions, this was explicitly denied by the creators of the show.
(The following is taken from the compilation post which gathers all of the official statements regarding Code Geass and
Lelouch's officially confirmed death.)
For a full overview, follow the link.
In Mook Animedia (28 January 2009, p.89-90) there was an interview (see 2 pictures below) which explicitly denied that Nunnally was seeing visions or that those images had anything to do with codes or geasses.
Q: "How did Nunnally managed to realize Lelouch true intention, when she touched his hand at the end?"
Staff member K: "The way Nunnally can tell that someone is lying, just like she was able to tell that Lohmeyer was lying to her, is that she can feel the hand of the person she is talking to is sweating or lightly trembling. It's nothing like Geass or some special ability like that."
Staff member Y: "Yes. So, she simply came to conclusion [Lelouch was lying] by herself, because of this ability."
Staff member K: "She is Marianne's daughter and Lelouch's little sister. Two months have passed since that defeat of Schneizel and for this two months she's been wondering constantly about what had happened, like "why it happened?" and so on. So when she touched Lelouch's hand at the end she felt that he is calm, she put the two and two together and realized the truth. Of course, we know that in anime, it's hard to explain things like that, but yeah, please accept it like this kind of romantic idea we had."
The anime itself also makes it clear that Nunnally did not see anything:
In R1 episode 11, when C.C. is feeding shock images to Suzaku she says:
C.C.: "I'm just feeding him some shock images, I can't tell what he's seeing, though."
In R2 episode 21 C.C. and Suzaku have the following conversation:
Suzaku: "Was that what I saw when we met at Narita?"
C.C: "There, it was mixed with your personal consciousness. I'm merely guessing as I don't know what it was you saw."
Thus, the anime tells us twice that C.C. had no idea what Suzaku was seeing. That means she did not choose the images she was sending. If code bearers can't choose what the recipient of their visions is seeing, than neither can Lelouch, thus Nunnally seeing exactly THOSE images is highly suspicious.
But the real nail in the coffin of this argument is what exactly is shown during these visions: the recipient's own memories mixed with random shock images.
Not only do the images which Nunnally allegedly sees not contain any shock images and is the tone and stability of her images entirely different from what Suzaku sees (no bright lights, no nerves tunnel vision), but the images which she allegedly sees are NOT her memories because she was not present during the shown scenes. Therefore it is entirely impossible for those images to be code visions.
C.C.'s words are confirmed when Lelouch touches her when she's feeding visions to Suzaku, she loses control and shortcircuits, making all three people recipients and as a result all three see a mix of shock images and memories of Suzaku, Lelouch and C.C. This is evidenced by the following images: we see Lelouch inside the vision, and a fraction of a second later we see both Lelouch and Suzaku together inside the same vision. Lelouch is right there, with Suzaku in a shared vision. Fortunately for Lelouch, Suzaku is too busy having the freak out of his life to be aware of anything. (Or maybe this was Suzaku's first clue on Zero's identity? Who knows?)
On top of C.C.'s words we also have audio and visual cues. Nunnally's alleged vision doesn't sound at all like the visions C.C. gave to her targets, and the animation style is completely different too.
Lastly, the chronology of the events just doesn't allow the images to be a vision she reacts to. Putting the events in chronological order we get: Nunnally touches a dying Lelouch, Nunnally acts shocked and gasps audibly, images are shown, Nunnally starts crying. It is clear that Nunnally's reaction started BEFORE the images are shown. How can she react to something she hasn't seen yet? Obviously she can't. And if she saw the images before her shocked reaction and her gasp, then why did they put the images after it? It's fully within the animators' power to show the images first, but they CHOSE not to. The only conclusion we can draw is that Nunnally's realization and shock do not stem from the images.
So, what does Nunnally see when she touches Lelouch?
The answer is simple, she sees nothing. If she truly would suddenly begin hallucinating because someone gave her visions, she'd freak out (like people did when C.C. gave them visions), but she didn't react AT ALL. If characters don't react to information, that means the information is non-diegetic.
To quote wikipedia: "Diegetic elements are part of the fictional world ("part of the story"), as opposed to non-diegetic elements which are stylistic elements of how the narrator tells the story ("part of the storytelling").
Simply put, non-diegetic information is information for the audience only, it does not exist in the fictional universe. All fiction make liberal use of this technique, the examples are legio. Non-diegetic information can be auditive (e.g. background music which tells the audience when a scene is sad/romantic/...) or visual (e.g. people's excessive grinning when they lie so that the audience knows it's a lie, but the victim doesn't)
Code Geass, too, uses loads of non-diegetic information. Examples are the red rings around people's eyes when they are geassed, Rolo's locket swinging which symbolically shows he is using his geass, the red sphere in which Rolo "stops time", etc.
Likewise is Nunnally's "vision" non-diegetic. She sees nothing, the creators want to make clear we understand that she finally understood her brother's intentions.
It is no coincidence that they show this "vision" when Nunnally touches his hand, it fits thematically with Nunnally's ability to know when people are lying by touching their hand. She does this several times in the show, for example with Suzaku and Alicia Lohmeyer. Here are screenshots of these scenes from R2 episode 7, R2 episode 15 (2 screenshots), and R2 episode 15 again.
We can even add the commentary track from the actors themselves. They were talking about Nunnally understanding her brother, but they never mentioned any form of vision or memory transfer.
In short, the anime itself fully contradicts the interpretation that Lelouch was sending his sister code visions, because it violates everything the show has told us about these visions.
Nunnally is able to see a person's intentions by touching their hand. This is stated early on in the show, and she is shown using it on Alicia Lohmeyer when they were discussing the plans for redeveloping the ghettos. Alicia said that it wouldn't be a big deal for the Japanese citizens, but Nunnally asked Alice to touch her hand and saw that she was lying, which prompted her to demand that the plans be rewritten so as not to hurt the Japanese anymore. (Season 2 Episode 8, I believe)
The flashback could have been for the viewers rather than something Nunnally actually saw directly.
Since Lelouch had activated the Code, Nunnally could see his memories when she touched him, exactly like what would happen if you touch C.C. Lelouch is alive. In fact, he is now immortal