User blog comment:MerlinUSA/Lies My Dragon Told Me/@comment-5577678-20130129184358/@comment-5102537-20130130001913

This thing about fate that was written in stone and the future that could have been altered were very chaotical, and one epsiode contradicted another. First it was said that Merlin's fate has been written since the dawn of time, The Crystal Cave proved clearly that the future can't be altered, as well as the Eye of the Phoenix did, then Kilgharrah implies that now Morgana is the darkness to Merlin's light because he sees too much good in people.

When a show deals with a fate of someone that can't be changed it should stick to it instead of changing it all the time. Merlin's future was either written since the dawn of time, as the Villia said, or it wasn't.

If I pretend that there was some logic at least in regard to this and to Kilgharrah, the dragon probably only knew about Merlin's future in a particular time/future but not exactly about the way he had to go to reach it (aside from the fact that he actually didn't reach his goal and didn't fulfill his fate in the end, which is another story), which means that Morgana's evilness and her opposing him and everyone else was part of the whole story and Merlin's way. In order to find some logic in it, Kligharrah knew how it all would end but not exactly what will happen along the way. He warned Merlin about Morgana but even if Merlin (or anyone else) had killed Morgana much earlier, something else would have happened that would have made Merlin do what he did and would have made things happen the way they did until the very end (of the show).

All in all, due to plotholes, lack of explanation and the terrible and disastrous end, there was no real continuitiy and we can only guess without ever getting an answer.