Connla

(コンラ) is the son of Cú Chulainn and Aife in the Irish.

Background
Connla was born from the relationship between Cú Chulainn and Aife. Aife, attacking the Land of Shadows while Cú Chulainn was training under Aife's sister Scáthach, was defeated by Cú Chulainn in a duel. He then perused her romantically for a time, but he eventually parted from her when leaving the Land of Shadows. He asked her that if she was to bear his child that she name the child Connla and send him to Ulster. Connla was to be tasked with three vows, "To not answer his name when asked," "To not change course," and "To not back down from a fight."

After the war with Connacht, Connla came down to the coast and started fighting the warriors of Ulster. He defeated any warrior who spoke to him, so the decided that only Cú Chulainn could defeat him. Although pleased with him not to go, he was unable to reject a royal order. Cú Chulainn fought him, eventually felling him with Gáe Bolg. As Connla died, he remarked that Scáthach did not teach him that technique.

Fate/hollow ataraxia
Connla is mentioned in Lancer's recollection of his past. He mentions that the vows were "the worst possible rules for my son."

Abilities
Connla was taught by Scáthach, able to fight on equal ground with his father. Cú Chulainn believes he didn't have any choice but to use Gáe Bolg.