In my After Cilmeri series, William de Valence is an long time supporter of Edward I, who resents David’s rule and ends up rebelling against him. I wrote him that way, because I believe it to be in keeping with who the man really was.

William de Valence was the fourth son of Isabella of Angouleme, the widow of King John of England, by her second marriage to Hugh X of Lusignan. Thus, he was half-brother to John’s son by Isabella, Henry, who became King of England on his father’s death, and uncle to Edward I.

When Henry invited William to England, as things had grown difficult for him in Poitou, thanks to the French conquest of the region, William landed on his feet, marrying an heiress to the William Marshal estates. Thus, through her, William became the Earl of Pembroke and the earldom of Wexford in Ireland.

William’s high station in Henry’s court created resentment among the English barons and was one of the reasons for the Baron’s war (ending in 1265). William accompanied Edward on Crusade, and then upon Edward’s ascension to the throne after his father’s death, William continued to find royal favor. He was one of the generals in Edward’s war against the Welsh that ended in 1283 with the capture of Castell y Bere (which he orchestrated).

https://en.wikipedia.org/wiki/William_de_Valence,_1st_Earl_of_Pembroke

He was buried at Westminster Abbey in 1296.