Board Thread:Rewatching "Merlin" - Season One/@comment-5102537-20130330123307/@comment-6905051-20130404104728

But end of the day, Morgana was the royal ward, with some amount of protection, merlin was a servant a bere nobody. His secret was too much precious to reveal. Even when he was trusted servant of king Arthur, one word from the Queen and he was thrown into jail with mere suspicion and no investigation, no bail, nothing.

The great dragon  too,repetitively told him not to trust Morgana. Also once he let out his secret, Morgana was smart enough to deduce all the happenings around him and Arthur has been Merlin's doing, she could have found out where he disappears at the middle of the night to seek advice, known about excalibur. She could  use it to blackmail him into doing her bidding too. I mean she had this naughty/evil streak all along. And Morgause came to Camelot with a reason, it was not just killing Uther. She wanted to reunite with her sister.

For Merlin, it was too much at stake to reveal his true nature. And his instincts were right. He did not hesitate in front of Freya to reveal himself because somehow he knew she will never give him away.