Dunstan le Fey was born to one of the oldest and most notorious families of the wizarding world. The le Feys. He grew up very lavishly, and was always a very bright child. Unlike the rest of his family (bar his sister Sabrina, who went to Beauxbatons), Dunstan was not sorted into Slytherin. He instead was put into Ravenclaw, much to the disdain of his family. But nonetheless, at least it was not Hufflepuff, according to them. Dunstan was a relatively happy child, until the unfortunate night.
Dunstan's bubble was soon to be burst abruptly. He was about to get a reality check that would scar him for the rest of his life. Perseus, the eldest child, and heir to the le Fey name. Perseus had involved himself with dark wizards, and had turned a traitor to the Ministry. The group of Wizards had been targeting ancient families - destroying their lineage and looting their homes. The noble house of Merlin was their next target - and with Phoebus wrapped around their fingers, it was almost too easy.
It was Halloween - Dunstan was 16. As he feasted in Hogwarts, his parents - Mortimer and Persephone dined at their home along with Dunstan's siblings; Perseus, Phoebus and Sabrina. They attacked in the dead of the night, killing Persephone first, then Mortimer. Both put up a fight, but they were caught off-guard, and were at a disadvantage. Perseus, who was dumbstruck at his 'friends' actions, tried to stop them and save his parents, but they tortured him and slowly killed him.
Sabrina and Phoebus were told to hide by Mortimer before the dark wizards entered, and they viewed the brutal murder of their family from the gaps of the large wicker laundry basket. Phoebus, only 10 years old, escaped from Sabrina's clutches and ran, crying to the body of his dead mother, only to be stunned then killed, too. But the wizards were not done yet- they looted the familial riches and trinkets, ornaments, money and anything of value. Sabrina, who was forced to witness her family's merciless and unnecessary death, grew cold and unforgiving. She notified Hogwarts, where Dunstan, was studying that he was the heir to the Le Fey name.
Dunstan was given leave from Hogwarts, for a while, needed to mourn the deaths, but he couldn't take it. He couldn't sleep in the empty mansion. Visions of his parents and brothers haunted him during both night and day. He shut out his feelings, crying silently to himself, alone. Unlike Sabrina, who outwardly displayed her sadness and coldness, Dunstan hid it. The two are very similar, in that she grew cold on the outside, Dunstan grew cold on the inside. He went back to school, focusing all his energy on his work and studies. But never forgetting.
Even after graduating, Dunstan still has an air of cold professionalism. He doesn't open up to people and generally remains quite closed and secretive. He now works as a PA to Noah Magic.