“Le Fay” indicates a “magical being”. 
Clover would of course have heard of Morgan le Fay

And in case you’re worried about poor child Heather being traumatized by her kidnapping, don’t be concerned.  The Prime Witch chewed the Elves out for their reckless behavior, then she moved Heather’s whole family to Alf-Ridge so that Heather would have a normal family life. Plus Heather soon got the backing of the Goddess Artemis which gave her more magical power than the Elves. Kith is actually a little bit afraid of Heather (although she tries to keep up a front that she isn’t).