He was a member of the family of the hereditary viscounts of Ausona, whose chief castle was at Cardona, although they also controlled the upper town of Vic itself.
[3] Arnulf's younger brother, the viscount of Ausona, recognised the overlordship of the bishop in the upper town.
In the mid-eleventh century, the viscount's authority in the upper town was replaced by that of the seneschal of the count of Barcelona when the latter inherited Ausona.
The lack of jurisdictional clarity that began in Arnulf's time led to open warfare between the bishops and the seneschals in the thirteenth century.
[1] In 1010, Count Ramon Borrell of Barcelona, taking advantage of the Andalusian fitna (civil war), invaded the caliphate of Córdoba.