Plot Involvement Edit
Fuse was first discovered in a crash site in the late 1940s. It's been kept a secret by the U.S. Government so that scientists could experiment, control, and weaponize the substance. Fuse violently mixes with and changes earthly materials. The outcome depends on the material it is mixed with, but the result is always lethal.
An unknown amount of time later, it was taken in by the Fuse Research Facility, headed by Freddy Fazbear. It is unknown how it came to boast properties such as granting people godly power, but nonetheless, Freddy Fazbear advertised it throughout the multiverse, subsequently trapping anyone who would attend the tour of the facility by providing them with the substance that would make them as powerful as a god.
The Ultimate Game Edit
It is mentioned that Freddy Fazbear ingested an unspecified amount of it sometime following the Fuse Incident, supposedly giving him the godlike power he believed it would and rendering him essentially indestructible, allowing him to occupy a parallel world assigned to him by the Arch Demon, making his base of operations in an abandoned Baxter Building.
When the player group stumbles upon him during the event of the Arch Demon's Downfall, the Fuse manages to completely protect Freddy from their attacks. Thus, they resort to tricking Freddy by trapping him in the Negative Zone forever.
Fighting of the Spirit Edit
It is mentioned in passing that Fuse is used to power up the numerous Monokuma bots assaulting Asgard in the second chapter, which allows them to stand toe to toe against Asgardian warriors, implying that the Revanchist happens to possess a number of it.
Its characteristics are entirely left vague. It never physically appears within the Murder Games, aside from some containers that supposedly held the volatile substance. Aside from the claim that it is able to grant individuals god-like power, and other odd powers like the bending of Traitor votes, very little is actually known about the substance.
It's known that the substance is used to improve the Replica Technology, and thus has been used by both Albert Wesker and the Mira-Curtiss Partnership in the past. It's likely currently being used by both Jade Curtiss' company and the Revanchist in their technology development.