I think that, as a general rule in Fate, characters are either “elevated” to being a hero, or made out to be worse than they are if they opposed the hero. Obviously it does make sense as a writing choice, but it’s very frustrating when interesting characters are relegated to being jokes or hated just because they opposed a cooler hero at some point in their original tale.
Karna and Arjuna are a super obvious one - Arjuna is consistently denied any sort of characterization because he’s constantly portrayed as being angry at Karna and vengeful in the main story, which makes him not be that interesting despite him being so fascinating in the Mahabharata. That, when combined with the figurative and literal white-washing of Karna makes him come off as super unlikeable.
Medea and Jason are another relationship where it really takes two to tango - they’re both pretty awful people and instead of them being portrayed as such (which would’ve been so interesting to see - I love terrible, toxic relationships in fiction), Jason is made to be a joke character that exists to be mocked and insulted. While LB5.1 does serve to redeem him, he’s still not treated as good or noble outside of that. And in contrast (in fgo especially), Medea is typically portrayed as a nice quirky witch girl, with many of her worst attributes being due to being placed under mind control by Aphrodite and then loving Jason, because she’s meant to be likeable. While in Fate Stay Night she’s absolutely more of an anti-hero (and imo way more interesting as a result!) she ends up losing a lot of those aspects, which is a shame because I think she is great because of them, not in spite of.
Fionn and Diarmuid are another example where in order to make Diarmuid look like a good person, Fionn (who is a fascinating and powerful mythological character in his own right!!) is portrayed as an unreasonable asshole that constantly insults Diarmuid and is completely self-obsessed.
There’s also the case of Achilles, where while his opponents aren’t demonized, he’s still definitely made to look a lot better as a person than his mythological counterpart. His rage and anger, which defines Achilles is gone, and a lot of his worst personality aspects (like say, withdrawing from war and whining to his mom when his literal slave whose family he killed that he’s into is taken from him) are completely erased. This isn’t to say that I dislike Achilles as a mythological character because I do find him fascinating, but I feel like his portrayal leaves much to be desired.
Ishtar and Gilgamesh are a very frustrating set to me, because to make Gilgamesh and Enkidu look good/right, Ishtar is made to be a joke and the one in the wrong. This is especially unfortunate because Ishtar is so cool as a goddess - the duality of her being a goddess of sex and war, and the fact that the original myth has Gilgamesh basically slut shames her (despite the fact that he himself is kind of a rapist) make it super unpleasant to me that fgo uncritically just treats her as a nuisance and as a terrible person for killing Enkidu when there’s so much more to her, and when Enkidu and Gilgamesh aren’t perfect themselves (but those traits of theirs are kind of erased or minimized).
This isn’t even counting something like Iskandar and Darius because that entire rivalry is so poorly written and executed and Darius isn’t even portrayed as a person which is. Definitely not a portrayal I’m happy about, considering how fascinating the Persian empire and it’s history are.
