Board Thread:Rewatching "Merlin" - Season Four/@comment-5102537-20131130132300/@comment-5674726-20131214000318

Ongard Odin wrote: Unfortunately, yet more unanswered questions, we can assume that Morgana was captured after Aithusa who was threatened in order to force Morgana into surrender, however how Aithusa was caught and how Morgana was not there to stop her capture remains a mystery.

They interesting, possibly troubling thing about this for me is that it clearly implies that Morgana and Aithusa had developed a close bond before the latter was captured by the Sarrum. Not only would the Sarrum have had to know that Aithusa was Morgana's weakness for him to target her, they had to have been very close for Morgana to endure two years of captivity and torture rather than use her magic to escape.

By my estimate, there is at least a year unaccounted for between Seasons Four and Five.

We could be looking at a situation where Morgana spent a year without making a move against Camelot, coming to care so much for another living being that she would go on to suffer for their sake rather than saving herself. In The Dark Tower, Morgana is surprised to learn that Guinevere wasn't aware of her captivity so I think that it would be safe to say that she believed that Arthur knew what had happened to her, and likely concluded that he approved, which would have put an end to any thought that she might have had of walking away from Camelot and maybe trying to make a life for herself elsewhere, ie. rebuilding the Isle of the Blessed.