Luke Skywalker walks into a bar and orders a drink. Dr. Cornelius Evazan  grabs him, tells him that he is liked by neither the doctor nor his friend and then threatens to kill Luke. According to Wookiepedia, the online depository for all information about the Star Wars galaxy, Evazan threatens Luke because he is a sociopath. Evazan doesn’t want money or power or prestige or food or sex. He just wants to kill Luke because he doesn’t like him. The Emperor/Darth Vader/Grand Moff Tarkin may want to kill Luke to continue to hold onto their grip on inter-planetary power, the Sand People may want to kill Luke because he trespasses on their territory and they would like to take his stuff, and Boba Fett  may want to kill Luke because he is a getting paid to do so, but Evazan just doesn’t like him.
The example used here from Star Wars is an extreme example of the point I am building towards. For something more mundane, there are people I don’t like and I feel guilty about disliking some of them. It can be a personality issue, or their behavior or their voice, particularly on days when I am irritable. It can also be the circumstances under which we met or that I was decaffeinated. And, most of the time, I can be perfectly pleasant with the person I dislike–the rest of the time we can not interact. Certainly I wouldn’t try to kill that person. The point is that most of the time my dislike is not due to a rivalry for a mate/food/prestige/power or the external manifestation of a cultural discourse of alterity/machismo/nationalism/spirituality, although it may also be any of those.
I mention this because it is something that often seems forgotten when writing a historical narrative. The explanation for this is that the historian is supposed to find reasonable causes events that rely on evidence that is demonstrable. For instance, to say that two people disliked each other is acceptable, but it would be preferable to say that those two people disliked each other because they were rivals for m/f/p/p or that the antipathy is the externalization of a cultural discourse of a/m/n/s. Even an attested “s/he looked cross-ways at my spouse” provides a reasonable and acceptable explanation. Unexplained maugre doesn’t happen in history. Naturally. Well, not really.
Inevitably, there are explanations for the dislike, but they are just of the sort that are not passed down in the historical record or are terribly satisfying and, often, the picayune cause for dislike exacerbates the rivalry or the cultural discourse and vice-versa. I am not suggesting that historians should seek to explain interpersonal relationships through a simple love/hate lens. Rather, I am musing that when there is evidence for a dislike that stems from a conflict of personalities or other similarly nebulous explanations, those should not be glossed over in favor of the rivalry for m/f/p/p or a discourse of a/m/n/s.
To take one example from the histories of Alexander the Great, Craterus was, arguably, Alexander’s most skilled military commander after the execution of Parmenion and was reputed to be a friend to the king. Hephaestion was Alexander’s childhood friend and likely homosexual companion and was reputed to be a friend to Alexander. These two men certainly were in a competition for power within Alexander’s army when they drew swords and attacked each other while in India. Each had a different avenue to power and prestige within the army and each had his own partisans who participated in the melee. They were also manifesting an agonistic masculine Macedonian discourse and, at that moment, transcending the issue of alterity in order to come to blows several thousand miles from home. But there is part of me that suspects, without any specific evidence,  that pointing out the rivalries and discourses doesn’t actually explain why the two men didn’t get along. Maybe, just maybe, Craterus also told stupid jokes and Hephaestion made slurping sounds when drinking his wine. But this is the purview of the historical novelist more than that of the historian.
 Yes, he has a name. No, he’s probably not a real doctor. Yes, he calls himself a doctor. No, to the extent that the galaxy has bureaucratic regulations that control who is and is not a doctor across worlds, no world recognizes Evazan as a doctor because they think he’s crazy, but the galaxy was a big place so he could evidently pass himself off as one. Yes, there is an implied question at the start of each sentence in this footnote.
 And the other mooks. 
 Storm Troopers, Palace Guards, etc.
 If I remember correctly, Plutarch says that they didn’t like each other and both seem to have been notoriously prickly characters. But that isn’t much.
 Then again, it has been argued time and again for millenia that the purpose of fiction is to reveal greater truths than non-fiction ever can.