Alfred Darlton was the adoptive Son
During the Final battle, Alfred and his brothers forsoke their places on the evacuations, deciding to die with honor. When the Devastation hit, Alfred was the only brother who survived (his other brothers died in battle before the blast). He was pulled out of the wreckage of his damaged suit, and spent the next few days trying to make sense of things. Ultimately, he was unable to reconcile his patriotism with the fact that he and his comrades (as well as the Britannian civillians) had ben sacrificed on the alter of expediency, and as a result he became a member of the black knights (his goal being to save the common people from their leaders). He rose quickly, earning a position as Zero Squadron's second in command.
When the time came to infiltrate the day of founding, Alfred served as Kallen's escort into the ball. He left the party afterwords, fled to an airfield, and than joined his teammates. During the battle, he fought his old mentor, Gilbert GP Guileford, and exchanged heated words. Alfred won on account of his superior suit.
Prior to the Devastation, Alfred was a devout Britannian patriot, who fully believed in it's ideals. The shock of being abandoned to die by the very government that he had devoted his life to in a cataclysm that the government itself had unleashed shattered his idealism, and while he did respect some elements (his old mentor Guilford), he felt nothing but contempt for the ruling class. He also learned to overcome his distaste for the numbers, and no longer sees a distinction between Britannians and Japanese. However, like the rest of the team he distrusts members of the Chinese federation.