Approximately six months ago, the universe experienced a catastrophic collision of dimensions, creating a massive rift in the solar system of Earth-617 (original Mutant Exodus timeline).
In this initial event, cities and towns all across the globe were rocked as various timelines crossed and merged, forever altering the landscape and even outright levelling some cities. Miami is a wasteland. Many people, animals, and objects manifested in this dimension.
Smaller rifts have opened at random since then, with more Extra-Dimensional Entities (EDEs, also called "outliers" or "rifters" in a derogatory slur) emerging from the portal anomalies.
Since the initial impact, SHIELD has set up a situation room that monitors the globe for the manifestation of anomalies via satellite. Agents have been dispatched to major urban settlements because of the large volume of arrivals in already heavily-populated areas. Smaller anomalies are addressed by mobile units that deploy as quickly as they are able.
EDEs are identifiable by a trace amount of radiation that lingers on them for a time after manifestation. SHIELD's technology detects both the temporal anomalies and this chemical trail, and they use it to locate those who come through the rifts in order to document their arrival and process them for citizenship.
The US government has taken a more aggressive stance, declaring that outliers should be chipped and catalogued, while still other politicians support rounding them up into camps "to prevent corruption of this dimension." This has led to tension between federal immigration agents and SHIELD, which does not follow this proposed procedure.
The overlap of dimensions is evident across the globe, with cities vastly ranging in technology and development from one neighborhood (or even block) to the next. The world is irrevocably changed. Some are eerily normal in appearance, having been merged with similar dimensions, while still others were spared entirely. There seems to be no rhyme or reason to how things collided, and SHIELD is still struggling to make sense of it.
