Brief timeline:
At some point in the old fortress, HugoLuman creates a tardis like time machine, by exploiting the curious nature of DF cage traps. (They can apparently hold and infinite number of creatures!)
His experiments with the time machine expose him to the omnipresent "truth" of time. This causes him to go apeshit bonkers, causes a paradox, and causes him to manifest as 2 discrete beings as a result. One is the evil hugo, the other is the benevolent hugo.
Towards the end of the last fortress, the time machine malfunctions, blows up, causes a thermonuclear catsplosion by crossripping with a dimension populated excusively by nothing but cats, before exploding itself. This explosion traps evil hugo in the cat dimension with no way out.
Several weeks pass, and a new fort rises on the edge of the old one, seemingly after several decades of temporal displacement, given that whole religious orders have risen up.
ZTG's medding causes good hugo to obtain magical powers allowing him to move between dimensions at will. As a consequence, since they are the same being, evil hugo also obtains these powers.
In an attempt to prevent the return of evil hugo, they attempt to bisect good and evil hugo. This has....undesirable effects.
Recently, eric made a deal with the "nobility god" that forces him to offer assylum to spirits if they don't want to go where they are supposed to go when their bodies die. This is in direct contravention of the compact my character made with the death goddess to be a necromancer. A wizard spat ensued, and a powerful magical device was sent across the void, causing unforseen consequences. Evil hugo notices the disturbace, and uses it to return, disguised as good hugo.
Also prevously, Mr Happyface had been on a cyberpunk junky "upgrade" fest, creating cybernetic abominations. Evil hugo is making use of Mr Happyface's equipment to forcibly alter the fortress population for his own purposes.
Now, everyone is trying to repel the cybernetic obliteration of the fortress.