I was going to add --> And will pretend to be the good one, an example to follow.

I added this because I think Arthur's uncle is jeaulous of Uther because he took the throne instead of him and now that he has an opportunity, he's going to try everything to get it. But, since we know he'll have scenes with a lot of people from the cast, maybe he is going to pretend he's the good one and try to get along with Gwen and everyone else maybe saying he supports the Arwen romance etc.. but deap down he's not that inocent (and then he may look for Morgana, but I don't believe she knows about him). + I agree with nsk when she says Arthur's uncle knows something about Ygraine, and maybe he's the one who is going to tell Arthur the whole truth about his birth and his mother (which can be a good way to get revenge on Uther) :)

^hum it is obvious it will pretend to be good otherwise the dude is stupid ahaha <3 and i dont know why..i just FEEL that he is going to be a sorcerer ...the show is about magic so why not ?
indeed maybe the reason why he got banished from camelot was because of the ygraine stuff
why gwen's mother ? because
1) we dont know anything about her and the writors said we'll see more of gwen's storyline (in season 1=> father , season 3 => brother)
2) she could be ygraine's maid since gwen was morgana's maid so..

Same as Ritaprodz said. I think he mainly will be after the throne.

^u dont think he is a sorcerer or linked to magic ?

Well he could be. I am not sure. Like you said the show is about magic. So why not? :) But my biggest guess is that he is after the throne.

its quite obvious that he will be after the throne and since the show need a villian he may be a sorcerer so i choose that answer
a simple guy who want the throne? not interesting enough
i also agree with naima about arthur/gwen's mothers

I only don't think he's a sorcerer for 2 reasons:
1st) He's Uther's brother, they're from the same family and most of the people who have magic are born with it (even though some may learn it but that part was only explored in the first season, now everyone we see with magic was born with it or has people from their famly related to the old religion) and if Uther doesn't have magic, I don't think he's brother has...
2nd) If he has magic it will turn him into another "Morgana". Wanting the throne, being evil, having magic... I don't think the producers are going for that... But maybe.. Who knows ? x)

^hum morgana is uther's daughter and nothing say that her mother was a sorcerer , besides merlin is a sorcerer too not his family (or maybe i forgot some episodes ? O_o let me know)

another morgana ? i dont think so because maybe he wont be a spy (so lesss smirk) and he surely wont play the perfect smiling stupid brother in front of everyone (at least i hope so LOL )
and idk...merlin needs a villian and a good one !

No, it must have been her mother since Morgause is her sister and also has magic so... And Merlin has his father who was a dragon lord and in some way had magic. And Merlin has because he is part of the profecy he was destined to have it.
But maybe he'll be a sorcerer Idk.. x)'

^ah ok :)

i wish that nsk were a merlin writor <3 according to the last spoilers , u were again right !

The full line: He'll use Gwen's love to Lancelot to break Arthur's heart, and make Morgana able to take the throne... ;)
Yeah, inspirred by the legend! x)