I recently posted the final part of my grand theory on the COTF and BR, and included in that post was a lengthy section explaining how the mechanics of telepathy work in ASOIAF. Since the grand theory is super long and does not focus exclusively on telepathy, I made this separate thread just to discuss it. Some of it is a tiny bit out of context, but don't worry about it. Or you can take like 10 hours to read my entire grand theory first.
The mechanics of telepathy in ASOIAF can be difficult to decipher, but luckily we have some other stories written by GRRM to help give us insight. Let’s start with the basics. Obviously the first explicit example of telepathy in the story is when we see the Stark children begin to bond with their direwolves and have wolf dreams. Later this knowledge or warging is expanded so that we are now aware of general skinchanging of animals, dragon riding, and Bran’s creepy ability to skinchange Hodor. So one big component of telepathy in the story is skinchanging/dragon riding. Skinchanging is a big part of GRRM’s Thousand Worlds universe. Particularly, an enemy of mankind called the Hrangan Minds utilized telepathy to control various slave races of creatures and wage war against humans.
Jojen Reed introduces us to the second big component of telepathy, prophetic dreams. It seems that certain people can receive prophetic dreams, including at least Bran and Jojen. And it seems that a weakened physical/mental state can trigger the onset of these visions, like Bran in his coma or Jojen with his near-fatal Greywater fever. And the concept of sending dreams to manipulate characters has been used by GRRM before, particularly in the story And Seven Times Never Kill Man, in which men are tricked into burning their winter food supply and killing their children, which is essentially what the War of the 5 Kings was in ASOIAF. Additionally, a common characteristic of characters who receive dreams or spend time skinchanging is that they tend to forego eating, namely Bran, Melisandre, Lancel, and Maester Aemon. And if that’s true, it implies that Baelor the Blessed, who died of fasting and is generally thought to have been a bit crazy, was likely receiving many powerful visions as well.
Third, we are introduced to the general concept that telepathic abilities can be trained and/or amplified, particularly by darkness and trauma. The best example of this so far is probably Arya’s training in the House of Black and White. Arya is made blind, intermittently attacked by an unknown silent assailant, and surrounded by cats. Finally, after suffering a good deal of frustration, Arya is able to skinchange into a cat while awake and identify her assailant as the Kindly Man. Similarly, Bran is able to train his warg powers while in the darkness of the WF crypts, and he takes full control of Hodor for the first time when they are attacked by wights and in mortal danger. Additionally, it may simply be the fact that Bran is crippled that makes him powerful enough to skinchange Hodor. And just to drive this point home, we are explicitly told in TWOIAF that the priests of Boash back in the day wore eyeless hoods, because: only in darkness, they believed, would their third eye open, allowing them to see the "higher truths" of creation that lay concealed behind the world's illusions.
Fourth, we are introduced to the concept that drugs can affect telepathic abilities, namely sweetsleep for dampening telepathy, and shade of the evening and weirwood paste for enhancing it. This concept has been used by GRRM before, particularly in the story Nightflyers.
Fifth, we are introduced to the concept that dead telepaths can send their consciousness into something else when Varamyr dies and goes into first the weirnet, and then his wolf. Presumably, many COTF may be living second lives inside the weirnet and the animals of the woods. More specifically, it is implied that the dead COTF skinchangers actually jump from animal to animal over time. The reason I think this is because BR tells Bran that there are COTF inside 100% of the ravens around their cave. Given the scarcity of skinchangers (purportedly 1:1000) and the relative youth of these ravens, that must mean the COTF skinchangers are forever trading in dead ravens for new ones in order to live basically infinite “second lives”. Because if the COTF only got to live a single “second life” inside a single raven, there should really be zero ravens with COTF inside them. And considering that Varamyr’s blood went into the weirnet when he died, and that there are tons of COTF bones lying around the cave around weirwood roots, it seems that the weirnet is facilitating the process by providing a sort of permanent storage vessel for the souls of the COTF. This whole process may sound weird, but keep in mind that in Nightflyers, telepaths were actually able to basically download their consciousnesses into an advanced computer upon death, so really anything could happen. It’s GRRM.
Now, one aspect of telepathy that has not yet been made explicit in ASOIAF is telekinesis, or teke as GRRM calls it in his sci-fi work. It may be that whatever force is animating the wights is doing so with teke. We have examples of wights moving around without brains, like Othor’s severed arm clawing at Jon during their fight and a headless bear decapitating Thoren Smallwood. So it appears that this is not some kind of skinchanging similar to what we have seen, as the wights are dead and presumably lack consciousness, especially if headless. Additionally, the wights are clumsy, while reanimated people like Coldhands and Beric appear fully coordinated and conscious. This last detail in particular makes me think that teke is the likely explanation for how the wights move around, because it reminds me of another clumsy corpse from Nightflyers. Additionally, we learned in Nightflyers that gravity fundamentally suppresses teke abilities for some unexplained reason. Being in free fall or being in space greatly enhances teke abilities. The major implication of this for ASOIAF is that it may explain why Bran didn't die from his fall. The combination of being in momentary free fall coupled with facing death may have pushed Bran's mind over the edge and unlocked his teke abilities for the first time.
The last significant aspect of telepathy, and one that hasn’t yet been made explicit in ASOIAF, is the concept that telepathy is intrinsically linked to our emotions and to love. Specifically, in Nightflyers, it is stated explicitly that having sex with someone is the most potent method of forming a telepathic bond with them.
For the purposes of explaining the Master Plan of the Old Gods, the most important aspect of telepathy to focus on is the concept that darkness and trauma can unlock, amplify, and train telepathic abilities. And I also want to point out, since Red Priests play a significant role in the story, that staring into flames for hours on end is basically the same thing as being in darkness. Have you ever tried staring at a fire for a long time? It blinds you. If you don’t want to take my word for it, just listen to my good friend, Ser Davos Seaworth:
The guards will huddle close to those torches. A little warmth, a little light, they're a comfort on a night like this. Yet that will blind them, so they will not see us pass.
And here is another Davos quote:
He lifted his eyes to stare up at the torch. He looked for a long time, never blinking, watching the flames shift and shimmer. He tried to see beyond them, to peer through the fiery curtain and glimpse whatever lived back there... but there was nothing, only fire, and after a time his eyes began to water. God-blind and tired, Davos curled up on the straw and gave himself to sleep.
If staring into flames is effectively the same as wearing an eyeless hood, then Mel’s visions (as well as those of Thoros, Moqorro, and Benerro) may actually be from the Old Gods, and fire may have no special magical properties other than facilitating temporary blindness. So while most readers assume that Mel is using some sort of “fire magic” and that greenseers use some totally different type of magic, I really don’t see any functional difference between Mel staring into flames and Bran being in the crypts.
Anyways, I already mentioned the training of Bran, Jojen, and Arya, but there is a notably long list of characters who may have undergone some telepathic training/enhancement in order to influence their actions, primarily through powerful dreams/visions:
Dany was given shade of the evening and trapped in darkness with a group of powerful telepaths.
Ned had his leg badly broken and was later trapped in darkness in the black cells with little food or water.
Doran Martell has gout and is crippled in a manner sort of similar to Bran. And it appears he is at least able to receive communications from Marwyn via glass candle.
Bloodraven lost use of an eye, as did the whore Yna and probably Euron as well.
Varys was given a potion that paralyzed him and had his genitals removed (and heard a voice speak from the flames).
Similarly, the Unsullied have all had their genitals burned on the altar of their Great Goddess who’s name only they know, not to mention all the other traumatic things Unsullied go through in their training. Considering they have all received a universally high degree of telepathic training and will hypothetically obey their Great Goddess should she call upon them, the Unsullied are prime candidates for being enslaved by the horn Dragonbinder at the beginning of TWOW.
Theon has also had a few body parts removed, ostensibly including his penis, and his actions are definitely central to shit going down in the North.
Jaime had his hand cut off and almost died.
Tyrion had his nose cut off and almost died.
Little Finger was terribly wounded in his duel against Brandon.
Mance Rayder was mauled by a shadowcat.
Harlon Greyjoy was suffering from greyscale, couldn’t speak, was trapped in a windowless tower, and telepathically called out to Euron (who was likely blinded in one eye by that same greyscale epidemic) begging for death.
Euron’s crew of mutes have all had their tongues removed, in what appears to be a successful attempt by Euron to replicate his experience with Harlon. And then Aeron Damphair is tortured and kept in darkness by Euron to unlock his telepathic abilities, which will presumably be utilized in the upcoming naval battle to protect Euron’s ship from the krakens that Euron will summon to destroy the enemy fleet.
And speaking of mutes, Wex might be carrying out the marching orders of the Old Gods. He is certainly central to negotiations between factions in the North.
The Mad King was kidnapped and tortured at Duskendale. We don’t know the exact details of his torture, but we do know he descended fully into madness after this episode.
Jon was stabbed and reached out to Ghost as he died.
Robb was shot by crossbow fire and reached out to Grey Wind as he died.
Beric, Catelyn, and Coldhands all died and were somehow reanimated. Additionally, it may be that their blood was absorbed into the weirnet (like Varamyr) and that this was a necessary step in their reanimation (though that doesn’t really help explain wtf is going on with UnGregor).
Patchface also died and came back somehow and now recites prophetic nonsense to people.
Maggy the Frog seems to also be a reanimated corpse based on Cersei’s description, and death may have helped her to receive visions of the future.
Finally, I would like to point out an interesting parallel that GRRM has made. You know that feeling you get when you are reading a super good book and you basically block out everything else going on around you and just fall into the page? I think GRRM considers that in itself to be another method of telepathic connection, the only difference being that it’s a one way connection. The reason I think this is because we get a description of Sam and his time spent in the library at Castle Black:
Sam did not know how long it had been since last he’d slept, but scarce an inch remained of the fat tallow candle he’d lit when starting on the ragged bundle of loose pages that he’d found tied up in twine. He was beastly tired, but it was hard to stop. One more book, he had told himself, then I’ll stop. One more folio, just one more. One more page, then I’ll go up and rest and get a bite to eat. But there was always another page after that one, and another after that, and another book waiting underneath the pile. I’ll just take a quick peek to see what this one is about, he’d think, and before he knew he would be halfway through it. He had not eaten since that bowl of bean-and-bacon soup with Pyp and Grenn.
So again we see the same symptoms of losing sense of time, not sleeping, and not eating. A good book is effectively like a good telepathic connection. And along those lines, a library is comparable to the weirnet. In fact, you could make the case that the collection of human knowledge at the citadel may rival, or in a sense may even be a competitor to, the collection of COTF knowledge in the weirnet. The real difference is that the humans who accumulate that knowledge all die eventually, while the greenseers of the COTF may all be very much alive. And on a more interesting meta level, you could interpret this info to mean that GRRM himself is the ultimate puppet master telepath in ASOIAF, and that he is trying to manipulate all the readers into thinking certain things with his awesome telepathic powers.