The first members came from Vladimir the Great in Kievan Rus right? How did Scandinavians come to join the Guard? Why did the Byzantine Emperor hire Anglo-Saxons in the 11th century?
The Rus were Swedish settlers in Russia, and they maintained close economic ties with Scandinavia. The first 6,000 Varangian sent to Emperor Basil by Vladmir were mostly Norwegian and Swedish mercenaries, who he had recruited to cement his control in Russia, and whom he could no longer pay. Be Scandinavians themselves, these first guardsmen obviously told their neighbors about the great opportunity after they went home.
The influx of Saxons in the late 11th century was mostly displaced English thanes and earls, who had been stripped of their lands by the Normans. Saxon culture was similar enough to that of Scandinavians that they fit into the guard well enough.