Althea Walker was a favorite daughter of William Walker, the ruthless American adventurer who made himself the King of Bronze-age Greece. She was highly intelligent, and from a young age her beloved father taught her his methods of achieving and maintaining power - for example, that a ruler who punishes the bearer of bad news makes himself (or herself) blind.
She was away from the capital when Helmut Mittler poisoned her father and massacred all her siblings, leaving her the only surviving Walker. Accompanied by a band of her father's loyal followers and with carts loaded with machines and books, she set out for Ferghanna, there to set up a new kingdom, far away from any sea shore where she would be vulnerable to her father's Islander foes. Her intention was to avoid her father's mistakes, not strike too soon but rather quietly build up strength and bide her time until feeling strong enough to strike at them and avenge her father.
With that her role in On the Oceans of Eternity is concluded, with an obvious opening for a future sequel.