The abyssal domain is amoral with diplomacy, or at least has ideological priorities that lead them to send immigrants to "unproductive" factions.  The lack of leadership means that you will have little luck hoping for coherent support due to their military being ironically very disorganized from a command standpoint despite how orderly they seem from a tactical/strategic standpoint.

At least their tech is good enough that you won't need too many of them anyways.