Circumstantial simultaneity

Circumstantial sumultaneity is a concept that is responsible for a great deal of Weird Plot Shit and, depending on interpretation, may or may not be a type of Time Shenanigans. HS 5710 (describes) the concept as follows:
 * "Circumstantial simultaneity is a concept more complex than its temporal analogue, and is valuable for examining the properties of paradox space. It is the agent responsible for the major cosmic event which pre-extinction Alternians came to refer to as The Great Undoing. The same concept rules the innumerable lesser events by which this critical moment shall be catalyzed, including the break, my employer's arrival, the detonation of a very powerful bomb, and my own death. It is an abstraction weaving together the fortunes of otherwise perfectly disparate chronologies, such as those bound to a pair of distinct sessions."

Rather frustratingly, he concludes that
 * "It's not fully comprehensible to a mortal mind, and the length I will go to explain it to you will not extend beyond this sentence."

Circumstantially simultaneous events generally are not temporally simultaneous for the simple reason that if they take place in different continuities of time, as they frequently do by being in different regions of paradox space (e.g. different sessions), it is not possible to make meaningful temporal comparisons. However, events that are circumstantially simultaneous often have some kind of similarity of circumstance, hence the name.

Examples of circumstantially simultaneous events:
 * Rose and Vriska, both Heroes of Light, HS 5719 (duel with) Jack Noir. Furthermore, both are seeking to defeat him in part to avenge the deaths of those he has murdered: Rose avenging John, Dad and Mom; Vriska avenging Karkat, Terezi and probably the other remaining trolls. Finally, it is worth noting that both are killed as a direct or indirect result of the duels; Rose is directly killed by Jack, while Terezi kills Vriska to prevent the outcomes she has forseen in Vriska's actions. In fact, depending on the interpretation of 's clock, Spades Slick (who is the trolls' version of Jack) may have even contributed to Vriska's death by causing the clock to halt on 'Just'.
 * 's HS 5513 (birth) and HS 5977 (death); he HS 5732 (defines the alpha timeline) of paradox space as that which contains both events.
 * HS 6009 (The destruction) of the kids' universe by Jack Noir attacking Bilious Slick with the Red Miles, and the destruction of the trolls' universe by Spades Slick shooting . These two events were circumstantially synchronised in the Tumor, providing it with the mass-energy required to create the Green Sun.