Many thanks to
gealach-ros for posting
this. BE WARNED FOR THE SERIES 5 SPOILERS.
I am so incredibly thrilled to see Alvarr make a comeback. The guy had a ton of potential to be a dangerous foe for Camelot. He was able to manipulate Morgana (hardly a difficult thing, I know) and Mordred (who might have seemed a willing accomplice, but come on, he was twelve tops), and had a ton of charisma, which would have made him a great salesman on binding together the disaffected magic users into one band.
And in reference to something said in the earlier post talking about Mordred's recasting: Perhaps Morgana won't be having creepy!awkward!sex with Mordred after all. She had a thing for Alvarr, so maybe she'll be dragging him into her hut deep in the forest by the hair. Goodness knows that making up insane plans to take over Camelot and telling Agravaine to get lost and that she wasn't interested over and over again doesn't leave much time for her to get laid by some pretty boy toy.