Lancelot

ABOUT LANCELOT
Arguably the most famous Arthurian character, asides from Arthur and Merlin.  Lancelot was born the son of a Gaulish king, who was killed shortly after his birth by a Frankish enemy ruler.  Several weeks later, having caught the eye of Vivian, the Lady of the Lake, Lancelot was spirited away to her court and raised there until he was around 16, unaware of his true origins.  As he grew, he became curious about the land of other humans, and eventually Vivian couldn't persuade him to stay any longer.

Lancelot spent many years at Arthur's side, carried by the strength of his beliefs rather than a previous attachment to Arthur himself.  However, eventually, much older and beaten down, he began an ill-advised love affair with Guinevere, Arthur's wife, that went far further than either of them had expected.  Although he believed it to be genuine, true love, it is ultimately destructive.  Arthur is furious when he finds out, and is pressured by societal standards at the time to have Guinevere executed for treason.  Lancelot, in a blind rage, goes to rescue her, leading to the deaths of two of Arthur's nephews by his hand.  Being Gawain's brothers, Gawain goes after Lancelot with such persistence and force that he essentially impales himself on Lancelot's sword, unwilling to live without revenge against Lancelot.

Eventually, while Lancelot remains in hiding in France, he hears of Arthur's death at the hands of Mordred and knows that this is at least partially his fault, having created the circumstances for Mordred's rising.  Though he's no longer wanted by Arthur's men, he goes into religious retreat, essentially crushed under the weight of his own sin.  Lancelot spends the rest of his life praying desperately for forgiveness from God, and taking increasingly long fasts until his body can't take it anymore and he dies of the strain.

PERSONALITY
A man with a very straightforward heart.  Lancelot is rare in that he comes to the Round Table with no previous attachments to anyone else there; his motivation is purely ideological and curiosity about his fellow man.  He rarely laughs or smiles, though he isn't rude, rather formal in speech to a fault.  He idealizes chivalry and wishes to be a perfect, godly man.  As such, he tends to feel discordant when he can't live up to his own impossibly high standards for his behavior.

As a child raised by the fae, he carries their cultural norms and ideas, though he grows much more like the others in morals and expectations as time goes on and he doesn't return to Vivian's court.  In doing so, he has essentially rejected her offer of immortality.

APPEARANCE
He has long hair, just slightly below touching his shoulders, though he tends to pin some of it back to keep it from getting in the way.  His features are delicate, and when he first arrives at Camelot he has a rather child-like fullness to his face (though this vanishes with age).

Most children stolen by the fae are slowly transformed into fae themselves, and Lancelot seems to have stopped half-way through the process.  There's a slight point to his ears and an odd light in his eyes, though it wouldn't be noticeable if you weren't looking for it.