"You don't have to fear me."

Hell, Gilli had never felt so terrified in his life. Never mind the tone of voice, just the way the way the raven-haired boy lounging on his bed looked at him made the hairs of the back of his neck stand up. That deadly, scheming look where one held the fate of another in one's hand. A cold, calculating look. Teasing to be exact.

The raven-haired boy tosses the ring over and Gilli surmises that he's made a new friend.

But then, of course, those words have to be said… "You don't know what that's like for me."

"I do."

And perhaps raven-haired boy's reply is a little too quick because in that moment, Gilli's fear of the young man in front of him intensifies. Who is this mere servant boy to say that he is as powerful as he is? No ring, no magic. No hope of understanding. But in that moment when the servant turns around and closes the door, Gilli's heart skips a beat. His eyes widen a fraction of a centimeter. The ebony haired boy whispers a word into his hand and brings his closed fist in front of him. Gilli doesn't want to believe it, he doesn't.

Yet there it is. The burning truth of a flame resting in Merlin's palm. Gilli looks up and sees Merlin challenging him to look away. He can see it in Merlin's eyes. The mistakes and the regret. The old eyes of a young man. What is this boy remembering? What past mistake has caused him to act this way?

Nevertheless, it doesn't make Gilli any less determined to kill the king. If at all, his anger at Merlin just makes him want to carry out his plan even more. He understands though, when Merlin fights against him from the sidelines the next day. The subtle flashes of gold, the terse glances telling him I told you.

When Gilli leaves Camelot and bids Merlin farewell, the fear of the warlock still hasn't vanished. Such a soul with such a heart-wrenching past. A traveling minstrel once told Gilli that choices were the hinges of destiny. Sometimes there were many doors to choose from, and sometimes there was just one. Despite that, once you crossed the threshold, there was no going back. Choices, the minstrel had continued, were what defined a man. It wasn't the fame and the glory, it was the decisions and the man that it would eventually shaped.

So Gill wondered about the young man with the old eyes and he wondered if he would ever see him again. Choices, Gill thought. It was all in the selfless choices that Merlin would make.

I thought Merlin's interactions with Gilli mirrored the "could-have been" with Morgana.
Both are people who dislike Uther, who wanted to be respected and live out in the open, but patient Merlin comes along and well... you get a plot line.
Throughout the episode, I couldn't help but think that Merlin was remembering the mistakes he made with Morgana that turned her into the woman she is now.

So yeah, that's were this is from.