Ooh, bb, this is gorgeous. You've done a marvelous job with the coloring here; I love the effects that make it look a bit like paint! There's something in the spareness (and vibrancy) of the coloring that makes me think of medieval art, as lotesse says, which is just perfectly in tone with those stories. Really lovely costume design, too. I haven't read the fic (yet), but that definitely looks like Eilonwy to me ... there's a determined, focused look to her face that's rather spot-on for the character, particularly later in the series.