Kings

Poul Anderson, Mother Of Kings (New York, 2003), Book Two, Chapter VII.

A king has to travel around within his realm:

to be seen widely;
to confer with local leaders;
to be well informed;
to subdue resistance;
to make judgments;
to lead offerings to local deities;
to bestow gifts;
to spread the cost of his household.

At the holy boulder in a shaw on the island of Atley, Eirik Blood-Ax beheads a fat cow in a seasonal rite, sprinkles the worshipers with blood and asks the local goddesses for help. Today, we visited a rebuilt Saxon Shrine where bread and wine represent flesh and blood, worshipers drink well water and are sprinkled with oil and the Mother of God is asked for help. Nowadays, the kingly and priestly roles have been separated.

Kings also behaved in ways that we would consider childish. As soon as King Harald of Norway grasps a sword sent by the English King Aethelstan, the latter's messenger immediately announces that acceptance of Aethelstan's sword has made Harald Aethelstan's vassal! But Harald had neither known of nor agreed to any such contract. Thus, he cannot be morally, legally or constitutionally bound by any vassalhood to Aethelstan. Nor could Aethelstan have meant "...to lay any real claim." (p. 119). Maybe it is a warning: stay away from England. Aethelstan's father had defeated the last Danish attack, subjugated the East Anglian Danes and gained kingship over Mercia and Essex and allegiance and tribute from the Welsh princes. Aethelstan had taken Northumbria and subjugated the Scottish kings. With such strength in England, any further invasions from Northern countries will be resisted.

Harald replies by sending his youngest son, Haakon, for Aethelstan to foster, thus notionally making Aethelstan lowlier than Harald. The Norse bringing the child Haakon, like the English delivering Aethelstan's sword, were prepared to fight if necessary. Imagine conducting diplomatic negotiations on that basis.