King Aelfwine of Deira succeeded King Deira.
King Aelfwine of Deira was born to King Oswiu of Northumbria.
On 05 Aug 641 (or 642 or 644 depending on the source) King Penda of Mercia Mercian and Welsh army defeated the Northumbrian army at the Battle of Maserfield. The battle is believed to have taken place at Oswestry. Northumbria was once again separated into two kingdoms.
[his uncle] King Oswald of Northumberland (age 37) was killed. His body was subsequently dismembered with his head and arms mounted on poles. His brother [his father] King Oswiu of Northumbria (age 29) succeeded King Bernicia. Rhiainfellt Rheged Queen Consort Bernicia by marriage Queen Consort Bernicia.
Eowa King Mercia was killed (probably).
Around 645 [his father] King Oswiu of Northumbria (age 33) and Eanflæd Queen Consort Bernicia (age 18) were married. She by marriage Queen Consort Bernicia. She the daughter of King Edwin of Northumbria and Æthelburh Oiscingas Queen Consort Northumbria (age 40). He the son of Æthelfrith King Northumbrians and Acha Queen Consort Northumbria. They were half first cousins.
On 15 Feb 670 [his father] King Oswiu of Northumbria (age 58) died. In 670 His son [his half-brother] King Ecgfrith of Northumbria (age 25) succeeded King Northumbria. Æthelthryth Wuffingas Queen Consort Deira and Northumbria (age 34) by marriage Queen Consort Northumbria.
Bede. 679. In the aforesaid battle, wherein Elfwin, the king's (age 34) brother, was killed, a memorable fact is known to have happened, which I think ought not to be passed by in silence; for the relation of the same will conduce to the salvation of many. In that battle, one Imma, a youth belonging to the king, was left as dead, and having lain so all that day and the next night among the dead bodies, at length he came to himself, and sitting, bound up his wounds in the best way he could. Then having rested awhile, he stood up, and began to go off to seek some friends that might take care of him; but in so doing he was discovered and taken by some of the enemy's army, and carried before their lord, who was an earl belonging to King Ethelred. Being asked by him who he was, and fearing to own himself a soldier, he answered, "He was a peasant, poor and married, and that he came to the army with others to bring provisions to the soldiers." The earl entertained him, and ordered his wounds to be dressed; and when he began to recover, to prevent his escaping, he ordered him to be bound; but that could not he performed, for as soon as they that bound him were gone, his bonds were all loosened.
Bede. BISHOP THEODORE MADE PEACE BETWEEN THE KINGS EGFRID AND ETHELRED
In the ninth year of the reign of [his half-brother] King Egfrid, a great battle was fought between him and Ethelred, king of the Mercians, near the river Trent, and Elfwin, brother to King Egfrid, was slain, a youth about eighteen years of age, and much beloved by both provinces, for King Ethelred had married his sister [his half-sister] Osthrid. There was now reason to expect a more bloody war, and more lasting enmity between those kings and their fierce nations; but Theodore, the bishop beloved of God, relying on the Divine assistance, by his wholesome admonitions extinguished the dangerous fire that was breaking out; so that the kings and their people on both sides being appeased, no man was put to death, but only the usual mulct paid to the king for his brother that had been killed; and this peace continued long after between those kings and their kingdoms.
Kings Bernicia: Great Grand Son of Æthelric King Bernicia
Kings Deira: Great Grand Son of Aella King Deira