I Think Henry Was a Wise Man and Kept William and Isabel Close to Him

I do think that henry probably strategically kept william with him as much as he could, keeping him and isabel apart. If william and isabel had had children, theye would have been this rival dynasty available to take over if henry faltered. Then when william died, henry saw an opportunity to bring the n lands into the plantagenet family by marrying isabel to his illegitimate half brother, hameling. Hamelin was so impressed with his bride, and the status of his bride, that he actually changed his name to de warren sor although we've got a woman as the countess, the family name carries on because hamelin takes her name.