Like most of Corwin's brood, Princess Branwen is fine-featured, with glossy ink-black hair sharply contrasting against clear fair skin and bright pale eyes – in her case, a striking gray-blue that seems to carry a slight chill in its gaze, like chips of ocean ice.  Delicate of frame and small in stature, but quick-minded and uncannily perceptive, even as a child she always seemed to be something of an “old soul,” understanding and perceiving more than seemed plausible for a girl of her age.  She was never a natural warrior like some of her family, instead gravitating towards a prodigious intuitive aptitude for academic, mystical, and artistic pursuits, including having inherited her father’s musical gifts: her singing voice is a warm, crystal-pure soubrette soprano, and although she specializes in plucked-string instruments like guitars and harps, there’s not an instrument in the castle’s conservatory she can’t at least finesse a charming melody out of.  In dress, she favors her family’s classic heraldic colors: dramatic black, accented with a generous spangling of silver and diamonds, most often preferring to keep her flashing eyes the only actual spark of color in her presentation.  She's been mentioned by Corwin to be the spitting image of his own mother, Faiella.

She has always unabashedly cherished her many sisters and brothers, happily co-conspiring in her elder siblings’ exploits and adoringly doting on the baby twins.  Her relations with Corwin and Lorraine, however, have been rather more fraught.  Growing up, her behavior drew a steady progression from being merely independent, to stubbornly willful, to outright tempestuous rebellion.  Screaming matches between her and either or both parents when she’d been refused something she wanted, or required to do something she didn't, were family legend, ragestorms of terrible beautiful perfection.  If Father is caught in a candid mood, he might admit that he feels that Branwen was allowed to grow up too fast, learn too much magic too young, and take the Pattern far too early, on her fourteenth birthday.  Perhaps he simply lost the resolve to go on challenging her.  And as if to prove him right, within a few days of becoming Pattern-capable, Branwen abruptly vanished from the castle and wasn’t seen again in Avalon for nearly two years.

When she returned, she simply reappeared in her chambers one fine frigid winter morning looking none the worse for wear, attended breakfast as though it was perfectly ordinary, and civilly yet firmly declined to disclose where she’d been or what she’d been doing all that time.  This was, perhaps needless to say, somewhat a source of friction between her and her parents, but Branwen promptly established a policy that whenever they pressed her too insistently on the subject, she’d simply vanish again for another month or two.  For the moment, faced with the options of either literally caging their daughter or just letting the mystery lie, they seem to have opted for the latter.  Wherever she’d gone, though, she obviously found some semblance of peace there, since her explosively volatile temper with even her parents’ gentlest efforts to achieve any actual parenting of her has calmed somewhat.  She’s still about as governable as a hurricane, but at least she’s not screaming at them quite so much.  Though maybe that’s simply because they can’t really stop her any more from just leaving whenever she chooses to.  Perhaps more alarming though, she must have also found some significant source of learning: her sorcery is greatly augmented since she’s back, her skill clearly now on a level with her far older siblings.  Any inquiries into how she accomplished this have been politely yet non-negotiably deflected.