Mordred had told Morgana the true identity of Emerys being Merlin. He felt anger towards him and Arthur over what happened with his friend Kara. He felt vindicated at the sight of the sorcerer who lost his magic to the Magic eater knowing it would do the same thing to Merlin. Once the box had been sent to Merlin Mordred returned to his room. He got his bag to get something when he found a letter addressed to him.
My love Mordred,
By the time you read this you are either on your way to Morgana or have already joined her, I understand. I have much to apologize for.
Firstly, when you were a child I was told by the Great Dragon that you would be Arthur's downfall and that I should kill you. That is the true reason I was late in helping you and Arthur.
Secondly, the attack on the Druid camp while my fault was completely unintentional. I sent Morgana to the camp to get help but the former king thought she was kidnapped and when I went to bring her back I was followed. Still afraid of what the future held I tried to stop your escape. I didn't understand at the time why it hurt so much when you said you would never forgive me. I had been told repeatedly that I should have killed you because of the future but I always refused to kill you, and when we met again you stopped the men from killing us by taking us to Morgana. As Morgana had tried to kill us multiple times I felt it best to stay distrustful of you no matter how drawn to you I felt. Even after you stabbed Morgana to save us and The Key told me you weren't Arthur's Bane I was unsure because of the Great Dragon. When you became a knight and I helped you remove your cloak, being that close to you made my magic sing and I nearly went weak at the knees with my power wanting to mingle with yours. You always took my mind in multiple directions so I watched and as I watched some of the directions changed, with the change I started to hope. I hoped that we could be friends possibly more.
Now thirdly, I must apologize for the situation with Kara, even though I was not the one who betrayed you. I let jealousy guide my anger and I told Gaius everything I was feeling and about the vision I'd had of you killing Arthur and I believe he went to Arthur about Kara's escape. I am sorry my love. I wish I had told you when you were here but my fear was to strong. I have fallen in love with you Mordred however you feel about me.
I love you Mordred. I am so sorry. I hope the next time we meet it's not on the battlefield. I already miss you. I miss your eyes on me and your voice in my head. Your innocence when the other knights played pranks on you or when you asked a question. I am sorry my love goodbye.
With all my love,
Merlin
p.s. As I am sure you are still wearing your armor I must tell you I have enchanted it to protect you against most weapons, however as you often told me my love Be Careful.
When Mordred finished reading the letter he felt shock at what had been revealed to him, but also warmth at the fact Merlin loved him. Then he felt horror at what he'd done by revealing Merlin's identity as Emerys. Mordred wished he'd found the letter sooner so he could found someway to stop Morgana from sending the magic eater to Merlin, or even before he'd revealed anything to Morgana. He now thought that once Morgana had Camelot he could find Merlin and possibly a way to bring back Merlin's magic. Then he could talk Merlin into running away with him.