Dream self

A dream self is another feature of the wonderful world of the Incipisphere: an alter ego that's supposed to awaken whenever the real person falls asleep. Dream selves are not independent entities, but simply representations of the dreamers. All eight of the Homestuck Kids, all twenty four trolls, and the two cherubs have or had at least one, and only people who are fated to play Sburb have dream selves in the first place. Jade's has been a huge part of her life, while the other pre-Scratch kids are rookies who only become aware of theirs in Act 4. Jane's and Dirk's were awake before Sburb game started. Jane, however, only woke the day before she played Sburb, while Dirk had been awake a significantly longer time. Jake's dream self was killed using peanuts before he woke up and Roxy's was in a condition similar to John's (shortly before he woke up), sleepwalking but not being able to open its eyes until meeting god tier Rose.

Dream selves operate from lavish towers on the moons of Prospit and Derse, in dream duplicates of their real bedrooms. Jaspersprite has HS 3526 (shown inherent knowledge of the matter).

Interestingly, Sollux has two dream selves, one each for Derse and Prospit. This also creates an imbalance: in the Troll session there are 7 dream selves on Prospit and 6 on Derse. Aradia's dream self was long thought to not exist, due to her dying before her session began, but it was in truth asleep on the center of the troll's Derse. It was only awake for moments before dying and ascending to god tier.

Features
Dream selves are projections of what the players want themselves to be. While most dream selves exhibit only minor differences (such as their shoes (and also their rooms) being their favorite color), Tavros's dreamself is able to walk, and Vriska's dreamself is not missing her arm or Vision Eightfold. Terezi's dreamself remains blind, as she prefers being blind to being sighted. Equius's dreamself still has a broken horn and cracked shades, the reasoning for this not being explained in-comic.

Dream selves can fly, and Dream Jade could conjure up extra arms at a whim, so they have at least some ability to pull hitherto unforeseen powers out of nowhere, the way people do in dreams. Dream selves are usually asleep when the real self is awake, and awakening a dream self causes the real self to fall asleep immediately. Dream Dave is a slight exception, as he's been awake all along but is passive and occupied with his computer (Rose implies that this is because he was refusing to accept or believe his surroundings when awake on Derse, although whether this is the sole reason or not remains unknown). When Dream Rose catches his attention, Real Dave immediately falls asleep. Dirk shares this exceptional state and has learned to control it up to the point where he can switch between his dream and real selves at will.

Since a dream self serves as a person's avatar during their sleep, their mind seems similarly hazy to that of a sleeping person. Consequently, they act similar to "normal" sleeping people: free-spirited, absent-minded, immune to second thoughts, forgetful, and somewhat irrational. This is why the first thing Dream Rose and Dream Dave do when meeting face to face is have a dance party and why Jade's tender ministrations left Dave with a brainless feathery asshole as his Kernelsprite.

Prospitian dream selves see visions of the present, past, and future when the Prospitian moon passes into the clouds of Skaia. Dersite dream selves hear the whispers of The Noble Circle of Horrorterrors, during Derse's lunar eclipse, when the moon is furthest from Skaia, eclipsed by Derse's shadow, and thus closest to the Furthest Ring.

Using her dream self, Jade is able to control her Dreambot, which mimics her dream self's actions. Given that the Dreambot was an invention of Jade's Grandpa, this indicates that Grandpa was aware of dream selves.

Dream selves and related objects are physical and have been found in the "real" world. Several items from Dream John's room landed on the Battlefield. Lil Cal was paradoxically created because of Dave's fear of Lil' Cal. Jade's dream self was stuffed by Grandpa and later prototyped by Jade.

Awakening
Jade states that the method of awakening one's dream self is to face (often unpleasant) things one has not before, such as John learning what his father really does for a living (although this failed to wake him up completely). Though this is not directly seen, Rose and Dave managed to awaken their dream selves in the alternate timeline resulting from John's demise due to Terezi Pyrope. Rose managed to stay awake when she traveled back to the main timeline by going to sleep just before the alternate timeline's destruction, going on HS 3600 (to help Dave) HS 3601 (fully awaken) HS 3602 (his dream self). John is woken up in a different manner: being manhandled by Jade and then narrowly avoiding a gargantuan fiery explosion to the face.

Sollux's Dersite dream self was able to wake up after Feferi kissed his corpse, though his Prospitian dream self had already been awake. Vriska woke up after her original self was killed by Aradia. Karkat and Aradia did not wake up until the trolls' session was over.

Dirk HS 6354 (has always been awake) without realizing it as both his real self and dream self are awake simultaneously. HS 6464 (According to) Calliope, this is most likely a side effect of being a Hero of Heart. Dave was also HS 3543 (said to be) awake all along without being aware of it, as he had frequently had nightmares where Lil' Cal talked to him. This was possibly caused by being raised by Dirk's pre-scratch self as Calliope also stated that certain classes could possibly pass this side effect onto other players.

Three of the dream selves of the B1 kids and at least four of the A2 troll's have scrawled some manner of disturbing images on the walls of their rooms. John's room is covered in garishly colored scribblings of harlequins and insults. Rose's is covered in anagrams of "MEOW", with each letter corresponding to the nitrogenous bases of DNA (G, C, A, and T). Dave has glowing images of Sweet Bro and Hella Jeff, complete with JPEG artifacts. Tavros, Aradia, Vriska and Terezi had genetic codes on their walls, similar to Rose (T1CK, T0CK, 8R8K, H34DS), and Gamzee filled Karkat's journal, in an alternate timeline where it was not destroyed, with "honk HONK". It is only after the dream self's awaking that a person will be able to perceive these scrawlings.

It's possible that the dream self of one player in every session (potentially always the Hero of Space) starts out awake.

Use as an Extra Life
A dream self can be used as a sort of "extra life" within the game should the "real" self of a player die. However, this is not an automatic process and a dream self suffers the same wounds as the real self after some delay, as experienced by Vriska, John, Rose, and Dave. This implies that if some trigger event does not take place within some period after the real self dies, the dream self will die as well. Aradia's dream self was seemingly an exception to this, living on in a coma-like state after her death, this may have been linked to her continued existence as a ghost after her death - which may have either been a result of her or Sollux's Mythological roles or one of their respective psychic powers which involved hearing the voices of the dead and the imminently deceased, respectively. Otherwise, it's just more weird plot shit.

There are two methods to trigger the revival as a dream self. Being kissed by a prince/princess (in other words, any player) is one of them. Dying on the Quest Bed is the other one, but it's part of the more complex process of ascending to god tier. Both methods revert any damage the dream self has already "copied" from the dying real self.

When a dream self is used as an "extra life", or to ascend to god tier, it seems to lose its special properties, including the altered state of mind, although god tier status comes with a new set of powers and abilities.

Rose, Dave, Sollux, Roxy, Dirk, and Jane all "became" their dream selves through a kiss at one point. It's possible some of the other trolls lost their "real" selves, but since it has not been detailed it can be assumed most of them stayed their "real" selves.

Roxy HS 7366 (notes) that "", either reinforcing the fact that the dream self is a separate physical body, or implying that reviving a dream self via kissing is capable of "healing" more than just wounds.

Death
According to Tavros Nitram, not only HS 3836 (can dream selves die), but the trolls' all have. This turned out to be not quite accurate, as the majority died due to the destruction of Prospit and Derse by Bec Noir. However, at the time Vriska's dream self and Sollux' Derse dream self (as well as potentially Gamzee's dream self) had already been used to revive them, although this can still easily count as a loss of a dream self, since dream self lose their dream self properties when used as an extra life. This may be the manner in which the Trolls "die", as prophesied by Sollux Captor; Sollux himself mentions that he will die twice, correctly predicting the death of his waking self and one dream self.

Dream Jade HS 3840 (demonstrated) the death of one's dream self by means of a gargantuan fiery explosion in the face. This also caused her Dreambot to blow up. Later, Grandpa found Dream Jade and stuffed her, like he was himself, following a family tradition.

For Jack Noir-related reasons, Jake and Jane's dream selves died before they had even begun to play the game. However, Jane's dream self began to HS 6308 (Do A Lifey Thing) shortly after her assassination, and was later found asleep elsewhere on Prospit. Calliope's dream self was killed by their session's Jack Noir, who had been hired to do so by Caliborn.

After Prospit is destroyed, Karkat forbids all Prospitian dreamers from sleeping, and later forbids Dersite dreamers after Derse is blown up. Falling asleep with a dead dream self causes the players to dream of the Furthest Ring and the eldritch monsters within, appearing as a dream projection inside special "bubbles" glubbed by the monsters. Karkat and Jade were unfortunate enough to find this out firsthand, while Feferi intentionally went to sleep with a dead dream self in an attempt to prove that the Horrorterrors aren't as evil as they appear. Using one's dream self as an extra life either by either method has the same effect. Sleeping players who become their dream selves via dream self revival or quest beds after their waking selves die also create dream projections in the dream bubbles.

Like many other things, dead dream selves can be revived via prototyping; however, this results in the dream self becoming its own independent being. Despite this, they can still be used by a waking self to ascend to the god tiers, which causes the god tiered player to attain the properties of the other prototyping; for example, when Jade went god tier, she got the dog ears and First Guardian powers of Becquerel.

Trivia

 * All human players dream on the same planet as their paradox relations. John and Jade are both Prospit dreamers. Their ectobiological parents Jake and Jane sleep on Prospit in the new session. Likewise, Rose and Dave are Derse dreamers and their ectobiological parents Dirk and Roxy have dream selves on the new Derse.
 * With Aradia's dream self being in the center of Derse and Sollux having an additional dream self on Prospit's moon, the planets have, respectively, five and seven towers, which adds up to twelve, which would be the total expected number of towers for their session under normal conditions. Presumably there the number of crypt quest beds in Prospit and Derse's moon would match the uneven number of dream towers, with their being one in each for Sollux and none in Derse's moon for Aradia (being at the center of Derse instead).
 * The A1 trolls have the same dreamer planets as their dancestor counterparts, including Mituna having both a Prospit and Derse dream self. Damara's dream self outfit is torn like Aradia's.
 * Curiously, in the Pre-Scratch Kid and Post-Scratch Troll sessions, the last dream selves to awaken, not counting those who might have died beforehand and never could later, were those of the players who entered first and designated "leaders" of the other Heroes, in this case being John and Karkat.
 * This theory could either be supported or denied by the dream self awakening of Jane, the B2 leader. She was technically only the second to officially "wake up" in the Medium after Dirk, but Jake never got the chance to do so before he got killed, and Roxy's dream self still "sleepwalked" when she was asleep, which could be considered a form of alertness to allow Jane to wake up.
 * Various characters when waking up, have their dream selves, instead of merely falling asleep, dematerialize. The reason behind this has not been explained.
 * Caliborn is the only player whose dream self has never been shown at any point in Homestuck, assuming Meenah and the god tier Cronus seen in Ministrife ascended as their dream selves rather than their waking selves. (Though Cronus's dream self still has a pixel, seen here, which didn't make it into the actual flash for some reason.) Caliborn's dream self has only ever been referred to indirectly, being known to be a Derse dreamer and having hired Jack to kill Calliope's dream self.