The Trow, or Drow, are the a northern counterpart of the Elves from Germanic accounts, and the Si, Sidh, or Shee from Celtic accounts. They were called Trow or Drow in the islands north of Scotland, specifically the Shetland Islands and the Orkney Islands in the North Sea.
In the Germanic languages, the etymology suggests a meaning of "faith, belief", both in Old English and modern Danish. That Germanic naming parallels the Celtic meaning of the Tencteri/Tungri, the first german people, who name in Celtic meant "the faithful."
And in the early British Isles, where the language was a blend of Scandinavian and other Germanic tongues, we find the word "trow". For example in the English King James Bible, we find the phrase "I trow not." (Luke 17:9) It simply means "I think (or believe) not."
So the people referred to as "Trow" in the Norhern Isles, and as the Si in Scotland/Ireland, and as the Elves in England, Germany and Scandinavia, were known to be either benevolent or cruel people, depending on the context.
Copyright 2017, John D. Nelson