Prophet of Disdain
The Prophet of Disdain is a Prophet only known from a Halo 2 match held at E3. During this match, players used premade accounts with the names of Halo characters. One team played as Spartans and used Marine names, such as "Mendoza" or "Stacker", when the other team as Elites, using Prophet names including "Disdain".
Disdain is a feeling of contempt or scorn. As the Prophets names are used in irony, the Prophet of Disdain's personality would likely mean that he was self-loathing.