Eysteinn Haraldsson (died 1157) was a son of Bjaðǫk and Haraldr gilli, King of Norway (died 1136).
Following Haraldr gilli's death, two of his sons, Sigurðr munnr (died 1155) and Ingi (died 1161), jointly ruled the Norwegian realm as kings.
According to Haraldssona saga within the thirteenth-century saga-compilation Heimskringla, in 1142 Eysteinn and Bjaðǫk were brought to Norway from west-over-sea by three prominent men of the realm: Árni sturla, Þorleifr Brynjólfsson, and Kolbeinn hrúga.
Eysteinn was thence put forward as an adult son of Haraldr gilli who deserved a share of the kingdom.
Once his claim was accepted, Eysteinn was recognised as king.
The thirteenth-century texts Fagrskinna and Morkinskinna give similar accounts although these sources do not identify Bjaðǫk by name.
In fact, her name appears to correspond to either the Gaelic Blathach, Bláthóc, or Bethóc.

Overseas sexual encounters between Norwegian royals and foreign women was evidently not an uncommon occurrence at the time.
Certainly, the thirteenth-century Chronica of Roger de Hoveden (died 1201/1202) pointedly remarks upon the low-status of the mothers of Norwegian monarchs.
Such relationships offered young women an opportunity to produce a royal son, and thereby procure preferment for herself and her family.
Whether the women concerned actually pursued such schemes themselves is uncertain, and it is possible that they were instead selected by the kings themselves or proffered by their own families.
In any case, it is conceivable that Eysteinn and Bjaðǫk enjoyed the support of influential relatives who backed their claims.
Despite his apparent Gaelic background, however, there is no hint of Eysteinn's interest in his homeland after his arrival in Scandinavia.
Eysteinn jointly ruled as king with his brothers until the end of his life.

One episode that may have bearing on Eysteinn's Gaelic heritage is his raiding expedition along the eastern British coast in about 1151.
At about this time, Guðrøðr Óláfsson (died 1187), son and heir of the reigning King of the Isles, visited Norway and rendered homage to Ingi.
Guðrøðr's Scandinavian stay coincided with that of Nicholas Breakspeare, Cardinal-Bishop of Albano (died 1159), an Englishman who became pope in 1154.
The latter was instrumental in the creation of the Norwegian Archdiocese of Niðaróss, an eclessiastical jurisdiction that officially included the Diocese of the Isles in 1154.
Nicholas also apparently favoured Ingi as king over Eysteinn and Sigurðr munnr.
Guðrøðr's cooperation with Ingi, therefore, could have been undertaken in the context of avoiding having to deal with Eysteinn and his seemingly Irish or Hebridean kin.
Eysteinn Haraldsson (died 1157) was a son of Bjaðǫk and Haraldr gilli, King of Norway (died 1136). Following Haraldr gilli's death, two of his sons, Sigurðr munnr (died 1155) and Ingi (died 1161), jointly ruled the Norwegian realm as kings. According to Haraldssona saga within the thirteenth-century saga-compilation Heimskringla, in 1142 Eysteinn and Bjaðǫk were brought to Norway from west-over-sea by three prominent men of the realm: Árni sturla, Þorleifr Brynjólfsson, and Kolbeinn hrúga. Eysteinn was thence put forward as an adult son of Haraldr gilli who deserved a share of the kingdom. Once his claim was accepted, Eysteinn was recognised as king. The thirteenth-century texts Fagrskinna and Morkinskinna give similar accounts although these sources do not identify Bjaðǫk by name. In fact, her name appears to correspond to either the Gaelic Blathach, Bláthóc, or Bethóc.
Overseas sexual encounters between Norwegian royals and foreign women was evidently not an uncommon occurrence at the time. Certainly, the thirteenth-century Chronica of Roger de Hoveden (died 1201/1202) pointedly remarks upon the low-status of the mothers of Norwegian monarchs. Such relationships offered young women an opportunity to produce a royal son, and thereby procure preferment for herself and her family. Whether the women concerned actually pursued such schemes themselves is uncertain, and it is possible that they were instead selected by the kings themselves or proffered by their own families. In any case, it is conceivable that Eysteinn and Bjaðǫk enjoyed the support of influential relatives who backed their claims. Despite his apparent Gaelic background, however, there is no hint of Eysteinn's interest in his homeland after his arrival in Scandinavia. Eysteinn jointly ruled as king with his brothers until the end of his life.
One episode that may have bearing on Eysteinn's Gaelic heritage is his raiding expedition along the eastern British coast in about 1151. At about this time, Guðrøðr Óláfsson (died 1187), son and heir of the reigning King of the Isles, visited Norway and rendered homage to Ingi. Guðrøðr's Scandinavian stay coincided with that of Nicholas Breakspeare, Cardinal-Bishop of Albano (died 1159), an Englishman who became pope in 1154. The latter was instrumental in the creation of the Norwegian Archdiocese of Niðaróss, an eclessiastical jurisdiction that officially included the Diocese of the Isles in 1154. Nicholas also apparently favoured Ingi as king over Eysteinn and Sigurðr munnr. Guðrøðr's cooperation with Ingi, therefore, could have been undertaken in the context of avoiding having to deal with Eysteinn and his seemingly Irish or Hebridean kin.
Bjaðǫk