Alternate Universes

Iced
The 20XX Crusaders have been through situations involving. For one, the 20XX member Iced that is known today isn't from this universe. After being affected by the effects of Snow Halation Requiem, the original Iced had his soul removed and had it replaced with his Alt. Universe counterpart, whose full name is Rick "Cryogen" Lousible.

Hazel and Octave
20XX users Hazel and Octave are actually alternate universe counterpart of each other. This was discovered by them discovering their mutual hatred for Iggy from JoJo.