- This page is about the phenomenon known as the Scratch, for other uses, see Scratch (disambiguation).
In Sburb, a Scratch is an event that occurs in certain sessions. Essentially, it is a mechanism by which a session, and the universe tied to it, can be reset to an indeterminate point in the past. The process releases a great deal of temporal energy, and the universe will then redevelop differently and eventually produce new Sburb sessions possibly very different from the one in which the Scratch was initiated. It is a last resort for a session doomed to failure, with the intention being to attempt to restart with more favourable conditions.
The kids activated their scratch as part of their plan to get rid of Jack, devised with the help of the trolls. In Karkat's first conversation with John(from Karkat's perspective), John heavily implied that the kids and trolls would meet in person after the Scratch. Rose and Dave arrived in proximity to Aradia and Sollux, and met the other remaining trolls on the asteroid, brought by Sollux to the Green Sun.
The trolls can't see the future of the kids after the Scratch, possibly because the kids' entire Incipisphere ceases to exist. However, since this seemed to happen just as the Scratch was being initiated (and therefore the Incipisphere had not ceased to exist yet), it may simply be a mechanism to eliminate (or at the very least minimize) interference from other sessions during the process, which is very delicate and important. The trolls initially believe that the Scratch is responsible for opening the hole in spacetime that led to the Great Undoing – the arrival of Jack Noir.
This lead to them calling it "the Rift", but it was revealed that Jack was fleeing from the Red Miles on Earth (not realising at the time that they were his own doing from hours later). He then went on a rampage through the troll session, preventing the trolls from claiming their ultimate reward. This in turn led them to contact the kids and indirectly orchestrate the Scratch which led Jack Noir to the troll session in the first place.
Aradia implies that Jack flees the kids' session to avoid being wiped from existence; the kids have all avoided this fate as well: John and Jade by breaking through the fourth wall, and Rose and Dave by being far out in the Furthest Ring. Doc Scratch voluntarily provides information on the Scratch, as it is apparently part of his plans, but mentions that the mysterious rift in spacetime that happens afterward is "none of his business." In all Scratched sessions so far, Doc Scratch manipulates the players such that the Scratch would benefit his master Lrd English (the trolls' session bringing him into existence, the kids' allowing him to conquer Earth through the Condesce).
The Hero of Time in each session is given a device to activate a Scratch (John, a Hero of Breath, activated the B-universe Scratch because Dave was far off in the Furthest Ring at the time), although it is rarely used – both the troll ancestors' session and the kids' session are "unusual" in this respect (among many others). In the kids' session, the device the Medium has produced for activating the scratch is the Beat Mesa in the Land of Heat and Clockwork, a giant record turntable. In the A1 session, the construct is the Cardinal Movement, the comb and cylinder of a music box embedded in a block of crystal, much like the features of the Land of Quartz and Melody.
The construct must be scratched (literally) with a pair of very sharp needles (the Quills of Echidna) to activate the process. The involvement of the Quills in the Scratch may explain why in both cases Skaia displayed both the Time and Space symbols spinning as the construct approached. The scratched device rises to Skaia and sends out a request to Skaia to change the conditions of the session, along with the temporal energy required for Skaia to make this change.
Skaia's influence however is limited, and it can only do so much. It has full control only over the defense portals, and can reconfigure them to lead to different points in time. As such, it changes the history of the host universe by sending ecto-babies to a different arrival time. It seems Skaia also uses this to exchange the roles of the Scratched session's players with their Dancestors, presumably to ensure a significant difference in the conditions of the new session.
This has occurred in both of the known sessions. When the original troll session was doomed to failure, its players Scratched it, resulting in a new session in which they became the ancestors of the twelve player trolls who, in the original session, were their ancestors. Similarly, the kids' Scratch has put their ectobiological parents (Nanna, Grandpa, Dave's Bro and Rose's Mom) in their places as the players Jane Crocker, Jake English, Dirk Strider, and Roxy Lalonde.
When the kids initiated the Scratch in their session, past Skaia manipulated the defense gates' target location to change the history of the post-Scratch universe. In a way, it is like creating an alternate timeline inside the alpha timeline, meaning that the Scratch was destined to happen. When the original troll players initiated the Scratch, it allowed them to be born in the other session, sort of like a backwards working of the kids' Scratch. How this is possible, we don't know, but it is suspected to be related to the Session Glitch.
The phrase "to start from scratch" refers to the act of starting something over, from the beginning, where an initial attempt has failed and the following attempt is made with nothing carried forward from the first. It originated in the late 1800s in reference to the boundary or starting line of a sports game, which was often physically scratched into the ground.
The Scratch may also be thought of as analogous to a record scratch, a destructive sound produced when a record is forced to run backwards and then continue forwards from an earlier point. The record scratch is portrayed quite literally with the Beat Mesa, and symbolically with Disc 2 of Homestuck.
Scratch may also mean to destroy or undo (as in the phrase "scratch that"). This can reflect how the destruction of the universes created and gave power to someone who would ravage everything in sight, including the universes themselves.
In billiards, a "scratch" is a term for a foul, most often for the act of pocketing the cue ball. After a scratch, the cue ball has to be "reset" to its starting position. While scratching is to be avoided most of the time, there are f0r which it might be prudent t0 d0 s0. However, a player that scratches while pocketing the 8-ball immediately loses.
The trolls' universe was destroyed when Spades Slick "pocketed the 8-ball" (killed Snowman), which was synchronised, in The Tumor, with the kids' universe being destroyed by Jack Noir after he was forced out of their session by the Scratch. In other words, the 8-ball was pocketed while scratching, and both universes "lost".