Horeme is a minor and almost unseen character in Final Fantasy Tactics A2: Grimoire of the Rift and a member of Khamja. Horeme is a Dragoon who acts as Ewen's replacement after he is defeated, mostly rescuing members of the organization from being arrested in some quests. Since this duty is mostly performed by Ewen assuming the player does not kill him before completing these quests, Horeme can become entirely non-existent to the player.
Regardless, the facts that he fills in the organization's hierarchy vacancy and that Cid and Horeme are aware of each other suggest that he is, in fact, a high-ranking member of Khamja. Whether his job is truly a Dragoon or a look-alike as in Ewen's case is unknown, as he never appears in any actual battle.