I'm not exactly sure what book you are reading-- but Merlin could worn Arthur about Morguese, Morgan, Mordred, Lancelot, or Guenevere.
Well many people are still not certain whether it was a trance-like Morgana (in other words Nimeuh) or Morgana herself. I do though think that it is morgana trying to warn Merlin to be careful because she may of had another frightning dream like the one about arthur getting bitten from the creature which she did in the very same episode she warned Merlin in. She warned Arthur so now she probably was warning him because we know she cares for Merlin and Arthur. Basically, I really don't think it is Nimeuh because why would she warn Merlin about the dangers ahead. Hope this helped!
Arthur hasn't YET. Only Lancelot, Gaius, Merlin's mother, Merlin's friend from his old village Will and Merlin himself (obviously) know that Merlin is a sorcerer. Lets keep our fingers crossed that Arthur does find out, If Merlin tells Arthur, imagine Arthur's face, or if Arthur realizes Merlin is a sorcerer and confronts him, imagine Merlin's face!! Added by Queen Arwen: Arthur may not have found out yet, but apparently he will in Season 5. This is from reliable sources, and is not just hearsay!
Stephen Dillane was Merlin in 2004 movie King Arthur.
Arthur doesn't know yet.
he is a wizard from the time of King Arthur. Merlin helped raise King Arthur
Merlin, is a wizard and a great friend of King Arthur.
Merlin was Arthur's tutor when he was a child in the care of Sir Ector. Merlin was the one who brought Arthur to Sir Ector from Arthur's mother Igraine. Merlin is responsible for educating Arthur to be the king he is supposed to be.
merlin the enchanter was the person who raised king arthur and helped him
They met in King Uther's castle and they ended up fighting, Merlin didn't realise that Arthur was the prince.
Merlin
no but she has seen him!