From what I read, Matilda of Brittany of Brittany died in 1189, what if Matilda of Brittany survives and becomes the bride of Louis VIII in 1195, the main reason why Eleanor of Brittany's betrothal failed is that she is the heiress of Arthur and the Emperor opposed the marriage between Eleanor of Brittany and Louis VIII in this case Mathilde and Louis VIII's marriage would have no opposition, because she is not the direct heir.
If Arthur is still killed and usurped by John what would happen?
If Arthur is still killed and usurped by John what would happen?