Disclaimer: I own nothing, everything to do with Merlin belongs to the BBC!

Many thanks to MerlinStar for being an awesome beta again, I owe you big time, my friend!

As a sworn protector of Camelot, it wasn't often Sir Leon couldn't be located. He had taken his vows; his life was Camelot. He protected her walls, her people, her leaders. For that to happen, he had to be in view the whole time, had to make the people realise he was there to protect them. But for someone who was always in plain sight, it wasn't often he was noticed.

Undeniably, when he was needed on the front line, there could be no mistaking the knight. His build and height set him above other men, and no one could stand in his way when he believed he had a kingdom to protect. Undying loyalty to Uther meant he was trusted with the delicate tasks that others were not.

But even greater than his loyalty was his respect for the prince. He had watched Arthur from when he was a small boy, watched him grow from the arrogant prince to the careful leader. Leon would die for Camelot, any of the knights would. But Arthur would give everything.

It was that respect that had Leon keeping a closer eye on the prince than his duties demanded. People were so used to seeing him roam the grounds that they no longer noticed him. He was just there, like always. He wasn't even sure whether many would notice if he disappeared; he just seemed to blend into the background. But it meant he saw things, things that no one else noticed.

He saw the way Arthur glanced at the serving girl when he thought no one was looking. But Leon also noticed the way Gwen returned his looks after checking the coast was clear. There was not just a passing fancy between the two of them. It was not the case – as had often been in the past – where Arthur could use his title to get what he wanted and then drop the girl without a word. This was love, so genuine and fierce even a blind man could see it. A deep and powerful emotion that Leon knew would either make or break the kingdom. It nearly did destroy everything. Leon knew they were just lucky that Uther was blind to such things and didn't notice the way his son was behaving. Even when marriage talks arose and Arthur was adamant he couldn't marry someone he didn't love, Uther did not realise it was because his heart already belonged to another. But Leon did. He saw the way their gazes turned desperately, the way she would often slip into his chambers when the guards were looking the other way. He also saw the look on her face when she left again. It was love. Then there was the whole incident when Uther finally did find out, only to dismiss it just as quickly as a passing fancy. Leon had seen Arthur enchanted before, he knew this was more than that. But somehow, they had managed to escape, and their love had remained intact. Leon was happy for the prince. He knew Gwen of old, knew that the maid would be good for the headstrong young man, a way of calming him down and lifting his spirits when all else had failed.

Leon wished it was only love that he was witness to, but that was not to be the case. Arthur could be just as frustratingly blind as his father when it came to the king's ward. How they didn't notice the looks, Leon had no idea. But he saw: the occasional smirk when Arthur was drawn into another dangerous battle or quest, the way her eyes sparkled with ill-contained glee even as she laid a hand on the king's arm in sympathy. There was nothing he could do but hope he was mistaken, but as the days hurried on his feelings of uncertainty and unrest only grew. Morgana had returned to Camelot a changed woman, and if only the knight knew of what she was plotting, then he might be able to go to Arthur. All the knight could do was watch and wait, biding his time and making sure he tried to keep the situation as under control as he could. But even the Lady Morgana had fallen prey to the invisible knight, and wouldn't notice him lurking as she stole from her chambers in the dead of night. Leon just wished that the King, or at least, the prince would see it.

Someone else had noticed things weren't right though, of that he was convinced. Merlin. The boy had been a constant mystery to Leon from the moment he had arrived in Camelot. The knight himself had been away initially, but had returned to find Prince Arthur had gained a new manservant, one who had apparently insulted him in public and then proceeded to save his life. For most, it was a surprise when the young man hadn't instantly been dismissed, but Leon knew Arthur better than that. He knew how the young prince craved for someone to treat him just like any other person – and he suspected that this Merlin might be good for him.

And the servant had been, there could be no denying that. But there was something Leon couldn't put his finger on. From the very beginning, there had been something different about Merlin, a quiet confidence disguised under extreme clumsiness – although the knight was sure that wasn't an act , no one would be able to slip that spectacularly. It irritated the knight that he couldn't figure out what it was, however. He had thought he knew everything that went on in Camelot, so what was it about Merlin that seemed so mysterious?

He first realised that something was more out of the ordinary than he had believed when they had ridden out to confront the dragon. Leon had been watching, as always. Something had been disturbing Merlin greatly, more so than the rest of them, but with attacks to co-ordinate, he had thought nothing of it. The battle had gone as the knight had predicted, with him being thrown from his horse in only a matter of moments. With stars whizzing around his head, he had barely been able to move, but instead opted for doing what he did best. He watched and listened. And Merlin... Merlin spoke to the beast. He had dismissed it in a way not unlike how Arthur often threw the servant out of his chambers. And the creature had listened, and just like that, flown away. Leon's heart had been pounding frantically then. He hadn't seen that one coming, and that was unusual for the knight. With his body refusing to react, he had just lain there, wondering what else the servant was hiding. And then he had heard as Merlin told Arthur he had defeated the creature, and the prince's laugh of relief in response.

Leon knew he should report what had happened. A servant that could control dragons? Something was very wrong there. But by the time his body was once more responding to him, he had changed his mind. Merlin clearly wanted to protect Arthur as much as Leon did, why else would he claim the prince had defeated the beast?

So he did nothing, but continued watching. As he himself noticed the changes taking place in the king's ward, he knew Merlin did too, more often than not seeing the pair shooting daggers at each other from opposite ends of the room, once more believing that no one could see them. And no one else could, apart from the knight who was all but invisible. He just had to watch and wait, and their feelings could be read on their faces with ease.

When the knight had started putting his trust in Merlin, Leon had no idea. He watched more and more obscure attacks cripple his beloved kingdom, putting him to the test to defend her; not only outside attacks, but those from within as well. And each time Camelot prevailed. He knew it wasn't to do with their skill, or Arthur's leadership, but Merlin. Leon still didn't know how, he just knew the black-haired clumsy servant with an infectious smile was somehow saving the day. The man swore he would find out how, if nothing else so he could give Merlin the thanks no one else was offering.

It was the final fight against Morgana that made Leon realise what it was. When the warning bell had sounded, he had seen the fear in Arthur's eyes that Merlin and Lancelot had already been killed. The newly appointed knight was good, that was for sure. But what chance did they have against an enemy that was immortal? And Merlin was... Merlin. Leon knew it was no act that the boy was uncomfortable with a sword in his hand. The knight had thrown himself back into the fight with a flourish, determined to protect the king and prince, but that was when the enemy had all but exploded. They had been defeated. But Leon had seen the cup, knew it was only magic that would be able to go against Morgana and Morgause and still prevail.

Merlin had magic.

The loyal knight was more than sure of it, for it now suddenly explained everything. Leon had sworn his vows, had sworn as part of his duties that he would help in the fight against magic. It was his duty. So what was the knight to do? He knew that Merlin posed no threat; he would have killed Arthur years ago if that was what he wanted. But Leon knew it was down to him to protect the prince.

So that was what he did. Committing treason for the sake of a servant, he once again blended into the background, unnoticed but constantly watching. Telling Arthur would destroy the prince, turn him into a clone of his father whilst wrecking a powerful friendship. Leon had sworn to protect the prince from the moment he came into this world to the moment he left it. But not all threats came from a physical source.

Merlin had magic. Leon knew this. But he had sworn to keep Arthur safe. And he knew Merlin was better equipped to do this than he was.

So he did nothing. But simply watched and listened.

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