It all starts with an affair. His mother was a famous Danish Singer from some well known Danish Wizarding family whom was the eye candy to the well known Dark Wizard Jacob Davids - of whom was married to some homely Swedish woman. It's unknown if they had any other children or not, but regardless of that, one day, he got the said woman pregnant, but not before leaving her all alone.
As a result of breaking her vows of virginity - given that she was to be married to another, she was forced out of her family and onto the streets of Denmark's capital. She soon gave birth to a baby boy, but not before dying. Her magic didn't save her, like with He-Whom-Must-Not Be Named's own mother. But the thing is, is that the young Danish Singer appeared to have no love of Jacob, given how she spat his name on her tongue. She swore to the babe before she died that he'd never be like his father - by giving him the name Casper.
As such, he was raised by Muggles ironically. The Pure blood Wizard has no reconciliation of Pure Blood things and was utterly shocked when he discovered he had magic, even though for years he had been doing magical things.
Whenever he was cleaning up and he didn't want too, the pots and pans would clean themselves as he watched. Or the occasional broom would sweep away stuff all on it's own - but that didn't stop him from being abused. His caretakers hated him for some reason - most likely relating to his magic, and often hit him and left him out of meals for days on end - or even isolated him away from the others, like he had a plague. That kind of thing made him a very awkward and shy person, like he just couldn't control himself in all honesty.
However, that all changed when a Wizard from Dumstrang came to collect him personally. Usually Wizards didn't do that, but he was a rare pleb. He came from a male line of Dark Wizards, which to some in the Wizarding community meant that somehow he'd join them, even though he hasn't seem keen on being a Dark Wizard, and has shown no signs of even being good with the Dark Arts, that didn't stop them from being suspicious though.
So, they dealt with him, and even told him he was a Wizard before departing in a thing of smoke. He didn't understand how they did that, but someday he would - someday he'd even be one of them.
So, off he went to Dumstrang on his eleventh birthday on the wishes of said wizard. It was a bloody miracle in all honesty, but it did wonders for him though. He did very well in school - and actually was very naturally gifted wit the Dark Arts, most unfortunately.
His time in school allowed him to join the Tri Wizard tournament.. unfortunately, he wasn't chosen for it, but that didn't matter that much. All he knew in the aftermath is that he wished to stay in England.
Which he did indeed. Besides, it's a good opportunity to rid himself of the past anyhow.