Details of Eric's life are few, and this has caused the sometime King of Northumbria in the 940s and 950s with an Eric of Norway mentioned in Norse sagas who ruled the Norwegian Westlands in the 930s. This possibly erroneous conflation of the two gives us a richer history, but cannot be proven. If true, however, then Bloodaxe is the son of Harald Fairhair and half-brother of Haakon the Good, and left the kingship of Norway to rule over northern England.
At least we have evidence of his status in England from the existence of coins minted during his reign. Shown are coins minted at York with "ERIC REX" on them, accompanied by a sword.
The epithet "Bloodaxe" comes from mentions by a Norse poet writing in the 900s, and is given to him because he supposedly slew his half-brothers to ensure his rule over Norway. Other poets and historians refer to him as a "brother killer" or simply the he was vicious as a Viking raider. The Anglo-Saxon Chronicle omits "Bloodaxe" and refers to him simply as "Harald's son."
Let's talk about northern England. When Æthelstan died in 939, he was succeeded by his teenage brother Edmund. It seems that Olaf Guthfrithson almost immediately left Dublin to reclaim what he once claimed. He was joined by his cousin, Olaf Sihtricsson (known in Ireland and usually referred to in chronicles as Amlaib Cuarán). When Guthfrithson died in 941 or 942, Amlaib succeeded him. He had (for a time, at least) the support of Archbishop Wulfstan of York. Edmund then marched north and subdued Amlaib (and Wulfstan), and negotiated a treaty: Amlaib would be an ally and could hold onto Northumbria.
This second Olaf, however, was supposedly not as acceptable as the first, so Wulfstan and others helped drive him out in 952 and invited Eric from Norway to come and rule them. This is where he starts minting his own coins. Tomorrow we'll continue the back-and-forth possession of Northern England from Viking to Anglo-Saxon hands.
