Both CK and Discord has almost similar backgrounds - both are an embodiment of a fundamental force. CK and Discord both are foils to Keeper of the Light and Celestia - which is symbolic here as the setting is on Chaos against Harmony - both also have powerful motives that goes against that of light / harmony. Fighting style wise, Chaos Knight might seem to play with power alone but is actually played cunningly and can be unpredictable (both play style and literal unpredictability - with 3 Random number God based skills, and the highest damage spread, CK is like his namesake, chaotic, just like Discord)