Correction on the Season. Arthur it was revealed in Season 1 Episode 8: The Beginning of the End. After Morgana is caught Arthur tries to talk Uther into letting Mordred go because of his young age. Uther says it was best to do it now before he grows up and become stronger and attacks them. Arthur tells Uther we don't know if he will attack us. Later Morgana talks Arthur into helping him escape. It is not clear if Arthur sees Mordred in season two although we know Morgana and Merlin does.

Maybe, he is using a alias or maybe he talked Arthur into believing he would not use magic. After all Uther kept Gaius around knowing he had once used magic.

What worries me is that Mordred knows Merlin has magic and uses it. Mordred also knows that Merlin is Emrys.

I think Mordred is likely working under an alias. I have a feeling that he's going to be the one to out Merlin to Arthur. And even though it's gonna suck with all the angst that will ensue from this, I want the magic reveal so I want him to out him.

well i read on tumblr that Bradley/Arthur was heard calling Mordred Mordred...

Maybe the writers are going to give us another season of clueless Arthur, who has forgotten Modred as a young boy . Is anyone surprise!!!!!!!!!!!!!!!

@Joppa, really? So he knows that Mordred has magic and he accepts him? Well that makes all of this even more interesting. Also wonder how Mordred is going to justify betraying Arthur after he saved his life and accepted him into his court knowing that he has magic.

Well that's what i read, but I also read somewhere, in some article, that Arthur is still not ready to accept the magic. So this is all very confusing for me.

The actor playing Modred is about the same ae as Authur or a year or two younger, so therefore Modred probably aged through magic , hence Arthur does not recognize him, because Modred should not be this old yet, he was only about 11 yrs when we first met him, maybe even younger.