[They] regarded their loyalty to the Emperors and their protection of the imperial persons as a pledge and ancestral tradition, handed down from father to son.
— Anna Comnena, The Alexiad, Cap II
Vikings didn't merely make their reputation as cunning traders or ferocious self-serving pirates, but were also willing to fight for others if it served their interests to do so. As such, they and their children eventually settled down and served as mercenaries for a variety of leaders in different capacities in a wide number of European areas for an equally variegated roster of masters. In Southern Europe and the Near East, they were called "Varangopouloi" — meaning "Viking children" or "Varangian children", because these men were either emigrés from Scandinavia and Russia, or were themselves descended from the same. In any case, blood remains true with these men, for they continue using the old Viking weapons of roundshield and greataxe, although their armour and accoutrements are based on Byzantine fashion. Varangopouloi retain the anti-cavalry competencies of both the Scots Cliarthaire and the more cosmopolitan Galloglaich Infantry (from which they are descended), but while being tougher and stronger they are less mobile, thus making them best used for defence. Their cost and slow movement range, however, means that they should not be trained in large numbers, because they will sap most of your wealth — and if facing archer civilisations like China or the Italians, will certainly die horribly and quickly as well.
Most famous of all Viking mercenaries were the Varangoi or Varangian Guard, picked for their bravery and their loyalty (which lasted as long as the Byzantines had sufficient money to pay them), being known as men who "cheerfully hacked" their foes to pieces. Not all Varangoi were Norse, however — there is some evidence to show that non-Norse peoples who nevertheless had the same propensity as Norse-born warriors were also admitted into their ranks, such as members of the Anglo-Saxon aristocracy displaced from England by Normans in the 11th and 12th centuries.
- Heavy "semi-mercenary" unique axe infantry unit, slower but stronger and tougher than normal Galloglaich Infantry.