This is Pippa. Born into service for Maugrim, she, alongside 5 other white doves, are carriage-pullers for Bronwyn (Maugrim hires birds and uses them as one may use a horse, keeping them tethered to the ground as his way of controlling 'a little piece of the sky'). She cannot leave the martens estate alone without permission (which is rarely granted) from Maugrim, or unless Bronwyn manages to sneak her out.
Pippa is Bronwyn's best friend - they grew up together - both feel as though Maugrim has trapped them and they have had many a heartfelt conversation complaining about him. XD They are fiercely loyal to each other - Pippa has a very motherly quality beyond her years, which Bronwyn needs in her life, but she can also be very brave when occassion calls for it.
Although Bronwyn has talked of freeing her several times, despite risking her father's rage, Pippa will not leave her to face him alone.