Jeyne Arryn
The Maiden of the Vale: Lady of the Eyrie in her own right, defender of her seat against four cousins' rebellions — a ruling lady with sharp sympathy for queens the realm calls unfit to rule.
The fuller tale
Called the Maiden of the Vale, Jeyne Arryn rules the Eyrie in her own right — a position she has already had to defend, more than once, against cousins who assume a ruling lady's seat is an invitation rather than a settled fact, and who learn, each time, precisely how wrong that assumption is.
Her own experience fighting off rebellions mounted specifically because she is a woman ruling in her own name gives her a particular and pointed sympathy for Rhaenyra's cause — Jeyne understands, with unusually direct personal knowledge, exactly what the realm's resistance to a queen's rule actually looks like up close, having spent years absorbing it herself.
That sympathy translates into real support for the black cause once the war begins, the Vale's arms and authority lending Rhaenyra's claim the backing of a ruling lady whose own legitimacy has already survived exactly the kind of challenge the greens are currently mounting against Rhaenyra's.
The page and the screen
Jeyne Arryn's arc, including the specifics of the cousins' rebellions she survives, is developed in considerably more detail in Fire & Blood than in the show's current seasons, which have introduced the character but not yet dramatized the full history the book affords her.
Where they stand, season by season
Their fate — if death has found them, it is written here. Open at your peril.
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.