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 four of the Homestuck Kids and all twelve trolls have 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 kids are rookies who only become aware of theirs in Act 4.

Dreamselves 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 status.

Features
Dream selves are projections of what the players want themselves to be. While most dreamselves 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.

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 (what this means has yet to be explained). When Dream Rose catches his attention, Real Dave immediately falls asleep.

One reason why dream selves are not crazy death machines is the word "dream." The person is asleep. They seem to act the way people do in dreams: free-spirited, sincere, immune to second thoughts, and as dumb as a sack of hammers. 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 in 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 grandfather, 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. John, Vriska, Aradia and Sollux became their dream selves.

Each of the dream selves corresponding to kids in the medium has 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. Jade, whose dream self was awake the whole time, did not have this problem.

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 to help Dave awaken his dream self. Dave was 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. John is woken up in a different manner: being manhandled by Jade and then narrowly avoiding a gargantuan fiery explosion in 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.

It's possible that the dreamself of one player in every session(potentially always the hero of space) starts out awake.

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, see below). Dream Jade HS 3840 (promptly 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.

Apparently the dream self can be used as a sort of "extra life" within the game - at the end of Sgrub, Sollux and Vriska are using their dream selves as their "real" bodies. It's possible some of the other trolls lost their "real" selves, but it can be assumed most of them lost their dreamselves. 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.

A dream self is not freely usable as an "extra life", as it suffers the same wounds as the real self after some delay, as experienced by Vriska, after Tavros tried to fight the will to kill her on her Quest Cocoon, her dream self nearly bled to death, just as her waking body did. 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. Being kissed by a prince/princess (in other words, any player) seems to trigger dream self revival. Dying on the Quest Bed revives the player as well, with the added bonus of ascending to the God Tiers and recovering from any wounds the dream self has.

It appears that using your dream self as an "extra life" causes it to lose its special dream powers. It remains to be seen if has the same effect as a dream self death (ie. dreams of the Furthest Ring), if the dying player does not reach the God Tier.

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, 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.

For Jack Noir-related reasons Jake's dream self died before he had even begun to play the game.