Bostil wanted them because he coveted them and because he feared them.

It would have been a terrible blow to him if any horse ever beat the gray.
But Creech laughed at all offers and taunted Bostil with a boast that in another summer he would see a horse out in front of the King.
To complicate matters and lead rivalry into hatred young Joel Creech, a great horseman, but worthless in the eyes of all save his father, had been heard to say that some day he would force a race between the King and Blue Roan.

And that threat had been taken in various ways.

It alienated Bostil beyond all hope of reconciliation.

It made Lucy Bostil laugh and look sweetly mysterious.