The King across the Channel

Eleanor of Brittany, Queen of Aragon
On Spring 1203, Eleanor of Brittany would marry Peter II of Aragon in Anjou ceding Arthur’s claims to Comminges, Bearn,Bigorre, Couserans and County of Toulouse to Peter II of Aragon.
The marriage only assured a strong regency for the minority of James I of Aragon.
Arthur I of Brittany would reassure Philip II that he would still marry his daughter Marie as there is a threat of him breaking the betrothal in favor of another Princess, both Philip II and John I of England did not like his cession of claims to Comminges, Bearn, Courserans, and Bigorre of Arthur as they both have claims in it which is another reason why Philip II would not really support Arthur, knowing that he can betray him anytime, but he knows that Arthur would certainly abandon the betrothal with Marie in case he had gotten England and Aquitaine.
Eleanor of Brittany would bear three children named Constance(1204), Eleanor(1206), James(1208), and Sanchia(1212), James would be the successor her husband Peter II.
Eleanor of Brittany would witness her husband being crowned by the pope 1205 as a Catholic Monarch and have heard of his death in Muret in 1213.
Eleanor of Brittany would have suggested to her husband and arranged the betrothals and marriage of her daughters Constance and Eleanor to Henry of Castile and Philip of France, grandson of Philip II, but the betrothal of Constance to Henry ended up being for Ferdinand III of Castile and Leon while Eleanor would end up not marrying Philip due to his death in 1219 and she would end up marrying Bela IV of Hungary, the termination of the betrothal and death of Henry of Castile would end the betrothal of Eleanor of Castile to James and resulted in the marriage of James to Berengaria of Leon in 1224, James I of Aragon would arrange the marriage of his sister, Sanchia to Frederick II of HRE the widower of his aunt, Constance in 1224.
Eleanor of Brittany would send Aragonese troops for brother, Arthur in 1216 when he was chosen as King of England by rebellious barons of John which would lead to the rejection of Arthur in favor of Henry III in the same year when the rebellious barons switch their support from Arthur to Henry III.
After the majority of James I of Aragon in 1226, Eleanor of Brittany would retire to Fontravraud Abbey until her death in 1240 where she would be visited by her son and her brother.

Jeanne I of Burgundy
On 1205, Jeanne I of Burgundy would enter an alliance with the King of Aragon seeing that his relative is the count of Provence and sought to marry a relative of the King of Aragon, Peter II would ask who she would marry, his nephew, the heir to the count of Provence or his younger brother, Infante Fernando, Joanna would choose a marriage with Infante Fernando as the heir of the count of Provence is very young to her liking and such this would start the alliance of the count of Burgundy with the King of Aragon who has gained influence in the Holy Roman Empire and the Kingdom of Arles via the two marriages.
Infante Fernando would arrive in Burgundy in 1207 and rule with his wife as the Count of Burgundy and the two would have a two surviving children namely, Eudes b. 1210 and Marie b. 1218.

Barons war
On 1212, Arthur I of Brittany would marry Marie of France and was very much insistent on warring against the Plantagenets seeing that both Louis and Philippe would want to reclaim Artois which is held by Marie of Champagne and her son, Baldwin, but they would decide not to help him and decide to maintain a truce with Otto IV and John I of England and not support Frederick I of Sicily’s candidacy as the ruler of the Holy Roman Empire and maintain John I not wanting to fight Philip II and maintain the truce that they had made since 1205 when Arthur gained Poitou, Maine, and Tourraine but that is due to the betrayal of Arthur ceding Southern Gascony to Aragon which the French did not like and are trying to reverse by marrying Princess Eleanor of Aragon to Philip which would be destined to be a failure due to the death of Prince Philip of France.
On 1215, Arthur would accept the invitation of the Barons to take over England and he would betroth his daughter, Isabella of Brittany(1215) to Louis of France and have her in French custody and took his wife in the war and Arthur would be able to control half of England and the French would support Arthur I of Brittany in England and Frederick I of Sicily and the French would have taken control of Artois from the Flemish.
On 1216, the Barons would desert Arthur in favor of Henry III of England after John I of England had died in 1216, with Arthur returning to France embittered to the Capetians he would withdraw the betrothal of Isabella of Brittany from Louis of France.
When Arthur’s second daughter, Constance was born in 1220, he would betroth her to Louis of France instead of his daughter Isabella.