This is the best answer I could give...In terms of elemental opposites, Gray. In terms of long standing relationships, Gray. In terms of kinship, Gajeel. If there is anything involving dragons, Gajeel. If it's personailty types, stick the three of them in a room, lock the door and see who manages to make it out alive, assuming they don't just blow up the whole area.
I still think it's GrayIn terms of elemental opposites, Gray. In terms of long standing relationships, Gray. In terms of kinship, Gajeel. If there is anything involving dragons, Gajeel. If it's personailty types, stick the three of them in a room, lock the door and see who manages to make it out alive, assuming they don't just blow up the whole area.