Headcanon - Name - Wilkiam
William’s name is not truly William. Being that it was his fae family members that were around to name him after he was born, they named him Wilkiam. That is his true name. When Kheelan and Tristan placed Wil in the London Orphanage as a baby, the people there opted to change it formally on his records to William, deeming Wilkiam too eccentric and that the boy deserved a more proper British name.
Be it noted, using a Fae’s true name does bear power over them. Whether this would work on Wil at this point, being that he’s a mix of human and fae is yet to be known. His family didn’t think so when they gave him up at birth, which is why the orphanage had his real name, but since then his fae dna has spread and grown immensely through his biology and system, so who knows..