i was thinking a lot earlier about hornet's sense of morality especially when it comes to killing
basically i think its like. she will kill you if:
you're in her way in any capacity
she thinks youre mindless (animalistic, mind controlled, zombied)
if her "i must be on top, i must be the strongest in this land" territorial god instincts take over
if she can justify it to herself by using one of the above reasonings
and she wont kill you if:
you dont fit any of the above criteria
she likes you (may overwrite previous criteria)
point number 1: hornet is ruthless. she is not often cruel; shes actually surprisingly empathetic, for a demigod raised as a beast and princess both and then left isolated killing zombies for like 2 thousand years. but she will not let anything be between her and her goal. "standing in her way" can mean anything from actively trying to kill her to literally standing in front of a door and not budging.
as part of her empathy, this encompasses "standing in the way of things she cares about", such as widow controlling bellhart, or when sherma is stuck in whiteward.
number 2: isnt it fucked how many of the haunted people in pharloom are still alive and can be returned to normalcy once their haunting is severed, and hornet absolutely knows this after bellhart, but she kills them anyway? yes, they try to kill her first, but most of them are very easily ignored. most of them are regular people being mind controlled and/or zombies, theyre not difficult enemies. more on this later
number 3: main example is of course Grand Mother Silk. her initial reasoning is that she's standing in her way (perturbing her normal life- "Were I to flee now, I would again be pursued. Until I find the source of that hunger, and slay it, I will not be free"), then, because she gains some empathy for the people of pharloom as a whole and wants to free them. but underlying all of that, is the instinctual need to be the dominant one- only one god per land. it seems like a Higher Being's diet consists primarily of consuming other higher beings, so that they alone can rule. hornet has to actively steel herself and not let that urge overtake her. or you get the bad ending
tho i do think there's another instance of this, which had an explanation hastily added onto the game that didnt really leave anyone satisfied. to me this is the real reason she kills karmelita, even if she already has the other hearts. karmelita might not have been a higher being (i dont think? she maybe could be a low level one like Unn?), but she very clearly was one of the strongest people in this place. and she was a ruler. i dont think its out of left field to suggest hornet did it because she wanted to prove she was stronger. which leads me to:
number 4: i think hornet just likes to fight, and likes to kill and win, but she cant come to terms with that part of herself- shes always trying to supress her ugly instincts, and can't often admit that she not fully able to. so she comes up with reasonings and excuses for herself.
theres the saying that intelligent people believe stupid things because they use their intelligence to convince themselves theyre always right, and this 100% applies to hornet. she also uses her big brain to justify killing the haunted bugs i mentioned above, theyre controlled, theyre weak, they attacked first, never mind the fact shes a higher being massacring some random dudes. she also justifies invading the green prince's mind and then killing him, and maybe even phantom, since she could tell phantom just fought her because they were suicidal. she is empathetic, but that empathy is not the first thing she feels when encountering others, it comes after shes spent time with or thinking of them, and is usually something she has to consciously remind herself to feel. shes also able to justify killing her siblings, and later regrets not ever attempting to see beyond what she already believed about them.
whats interesting about hk and silksong is that the player's actions are meant to mirror the characters, and that often works really well. the knight isnt hollow because You aren't and you care about all these characters. and going back to karmelia, i think hornet fights her because of the reasons you do: it'll be fun, a challenge, and you really really want to win. that matches well with the dominating instincts born of her pale lineage, and the hunting ones from the weavers.