Grand Order

So going through all the shown Servants, there are a lot that we have info on, Jekyll, Scathach, Darius, and Arjuna. Of those, we have the most information about Jekyll because he's in Fragments. Scathach is mentioned in HA and Darius is mentioned in Zero. Arjuna is actually mused upon quite a bit by Karna since he is the main driving factor for Karna, at least in Apo.
Either way, here I'm going to try summarize the relationship between Karna and Arjuna in Karna's eyes, since that's where ...