Baela Targaryen
Daemon and Laena's elder twin, wild as her father, rider of the young she-dragon Moondancer — betrothed to Jacaerys to bind the blacks' two houses into one.
A soul of House Targaryen, born at Pentos, sworn to The Blacks — the Queen's Party.
The fuller tale
Season Two
In The Burning Mill — Moondancer's rider shadows the green host from the clouds. Criston Cole marches out with the green host, bending black-sworn Rosby and Stokeworth into line — and Baela hunts him from dragonback. In The Red Sowing — Flies patrol over a fleet her grandfather built and her family finally uses.
Where they stand. Rook's Rest and Dragonstone.
Their story
Daemon and Laena's elder twin is, by consensus of both tellings, the wilder and more overtly ambitious of the two sisters — born in Pentos during her parents' years of voluntary exile, and raised from early childhood around dragons, sailors and the general unpredictability of Daemon Targaryen's household.
Rider of the young she-dragon Moondancer, Baela claims her mount with the same impatient confidence her father is famous for, and grows into the war years as one of the black cause's few young dragonriders old enough to be genuinely useful rather than merely symbolic.
Her betrothal to Jacaerys Velaryon, her cousin and stepbrother, is arranged specifically to bind the blacks' two great houses — Targaryen and Velaryon — into a single unbreakable interest, a marriage of policy that both families treat as essential to holding the coalition together through the war's worst pressures.
How it ends for them
The chronicle records no death for this soul — they are living when the tale leaves them, or their ending is a page the maesters have yet to turn.
Their chapters, book by book
Where the page and the screen part
Baela's characterization is broadly consistent between the show and Fire & Blood, both presenting her as spirited and capable, though the show's aired seasons have given her considerably more direct screen presence and dialogue than the book's more distant, chronicle-style treatment of the era's younger dragonriders.
Their journey
Where the two tellings send them to the same place the road runs whole; where they part, the screen keeps the left and the books the right.