I always wish Kargath was more of a character. Think about what he must have been through, from Ner’zhul’s abandonment, to living in a wasteland world, to rallying the survivors under Magtheridon, then pledging allegiance to Illidan to help destroy the Legion by any means necessary. All the while, himself and his people are constantly on the verge of insanity.
I would have loved the evolving relationship between Kargath’s Fel Horde and Thrall’s New Horde, the tension and differing ideologies from different planets, each of whom sees themselves as the successor to the Old Horde.