The Failure Twins have many names, but they are most often called Safe and Deadly. They have no definite gender, and are usually referred to by the default for the language being spoken, although sometimes one is said to be male and the other female.
The one referred to as Safe has every known active defense or shielding ability, including several that can do severe damage, and the one known as Deadly has almost every known destructive ability. Neither of them can use more than a fraction of their powers at once, but even that fraction is quite extensive, compared to many Pacts.
As Deadly is somewhat erratic and highly prone to berserking, it cannot be safely deployed or stored without Safe to keep it contained, and for this reason Safe cannot be deployed alone either.
In appearance, they look like mostly identical, highly androgynous robotic figures, whose physical characteristics depend on their current specialization. The only visible difference between the two is the fact that Safe has white armor and Deadly has red, although their abilities, when active, generally take very different forms.
They upgrade themselves constantly, automatically copying Abilities as they come into being, but have never been reproduced, for several reasons.
They are also known as Sword and Shield, Sheath and Bomb, the Terrors, and possibly Triumph and Disaster, although this last may be unrelated.