The Ruby Roadrunners

Lancers and Light cavalry, the Ruby Wing, and the Roadrunner steeds they deploy are not only particularly suited to the dry, arid regions of the high ranges, but they are also specifically bred and trained to cover mountainous terrain at speed. Granted, the fact that the 'runners do have flight allows them to rapidly navigate the rough terrain. Though one might not consider the slight birds with their agile mounts to qualify as "heavy cavalry", their agility and swift, sure footing means they can level substantial damage on the attack, and are quite difficult to corner in defense.  Command of RR divisions often leads to administration and  training roles, taking advantage of the 'beak to the ground" style for which the famous "Eed Wings are often called the "Crimson Death Wing"