Board Thread:Series 5 Discussion/@comment-82.156.4.128-20121224212052/@comment-31421028-20170301074150

The ending of Merlin is very unique, actually.

It was clearly an open-ended. Some people believe that Arthur died, while others believe that Arthur is waiting to be reincarnated. So, it is possible that Arthur will come back later on, when Albion needs him the most, which probably means that Arthur will come in the late future, when the world is at war.

As far as Merlin's destiny is concerned, he DID succeed. Gwen would have allowed magic once again in Camelot, and before Arthur died, he united all the five kingdoms. So, Arthur and Merlin have so far succeeded in bringing peace in Albion.

It might take more centuries for Arthur to come back, when Albion is literally at it's end. That's when Arthur will come back. Merlin waiting for so many centuries shows his loyalty towards Arthur, and towards his destiny. (Although according to the actual legend, Merlin is dead.)

One thing that doesn't make sense, though is Aithusa. Merlin is the last dragon lord; he is the one who got Aithusa in this world. Still, Aithusa betrayed him and Kilgarrah. Aithusa remains a big mystery, why she can't speak, why she helped Morgana in the first place.