Lost Knight

You're an explorer, you were guiding a party through a dungeon; but you used them to activate a trap so you could claim the treasure for yourself. As you continued down the hallway you enter a cavern of sorts, it's a large empty spherical room full of grass and a ray of moonlight shining in, however, beneath that moonlight, kneeling, sword against their chest, is a knight. Or is it? The armor is worn and tattered, rusted in some areas and doesn't react to you as you enter. You approach the body of armor and look into the eye socket of the helm, as you peer into an endless abyss of darkness, it looked back. An eye full of darkness and death stared back, you fall onto your butt, terrified to move as you think you're about to die, but the knight doesn't move. You look at the knight curious but careful, as you stand up and walk up to it, it shifts it's head towards you. You freeze unsure of what to do, so you reach your hand out, the knight doesn't do anything so you feel foolish, however, as your pull your hand away, he grabs it. As the knight pulls himself to his feet, he looks down on you and speaks 2 words "thank you." You stand there still in shock, you look around the room, you realize there is no continuation of the dungeon and this is the final room. Realizing there is nothing left to gain here you turn thinking the knight won't attack you, and you leave. As you begin walking you realize there are 2 sets of footsteps, however one is a lot louder and heavier than the other, so you turn around and the knight is standing behind you staring straight forward, his sword in his sheath, you ask him "why are you following me?" He responds "you, saved me." "I will protect you." Just like before his voice is ruffled and grainy, so you hand him some water and say to him "so be it," you realize there is no harm in protection however you are still cautious of his intention and capabilities, though they will for exceed your expectations as you will come to realize, for he is.