Seriously, though, Mordred’s narrative as solidified by Le Morte d'Arthur does not work as a villain’s arc within a modern context. You can no longer have the heroes point to the character as a baby and say ‘he’s going to grow up to be the most evil evil that ever eviled, so you might as well kill him now’ while still retaining their status as heroic figures. More to the point, attempted murder of a baby immediately turns that baby into an underdog. Within a modern context, Arthur and Merlin’s willingness to kill Mordred as a baby (along with murder of countless other infants) flips the narrative structure. Arthur and Merlin aren’t heroes anymore. They are villains. And Mordred is now an innocent. More importantly, he is an innocent who survived a slaughter and modern framing says it’s his duty to avenge the countless other innocents who died in his place. Mordred’s narrative easily slides into a modern heroic arc because it actually closely mimics that narrative.
Also, fate is not the be-all-end-all that it once was. You cannot just say anymore 'this character is fated to be the most evil evil that ever eviled’ and just expect the audience to go along with it. These days that’s considered lazy writing. A villain needs justification for their actions and unfortunately Mordred’s justifications for bringing down Camelot are actually incredibly sympathetic. The whole baby murder thing is a good place to start. We can then move on to people judging him and declaring him to be evil for something he had no control over (child of incest). And then we get back to this whole prophecy thing where people are judging him and declaring him to be evil for something he has not done yet. It’s hard to root against a villain when they shine a light in all the heinous things the heroes have done because they have suffered at the heroes’ hands.
Look, I understand to a degree not being down with villainous narratives being repackaged as heroic or anti-hero narratives. Some villains need to stay evil and not be re-imagined as heroes just because they’ve become popular. But there are also some villainous narratives that were a trope for their time, but now that trope is incredibly problematic and needs to die and the best way to fix the wrong is to re-imagine the villain as a hero. Or, in the case of Mordred, that villainous narrative actually reads as a heroic one now.
Times change. Narratives change. Mordred’s narrative is not a villainous one. Not anymore.