"Guys, I only have so much salt.That is not a pet; that is a creature from beyond time and space with no concept of human morality."
Thaddeus Blackstone Granger is the son of Hermione Granger from the Harry Potter franchise and Harry Dresden (no; not Harry Potter, for once) from The Dresden Files. He has recently taken Bernie as his apprentice in magic.
Some time after Harry Potter defeated Voldemort, but reportedly before Ron proposed, Hermione traveled abroad in order to expand her knowledge of the magical community as a whole. Some time during her travels, she wound up in Chicago, acting as an assistant to the Warden known as Harry Dresden. While Hermione would deny it now, there was a mutual attraction between them. She was reluctant and hesitant in the beginning, but then she rationalized that it was not like Ron would ever find out about it, right?
Well, to an extent, she was correct, though there were repercussions beyond her relationship with Ron suffering; namely, a child. Not having the heart to go through with an abortion, Hermione opted to carry the child, whom she named Thaddeus before she left for South America to research native blood magic. Harry, with his life consisting of constant danger, left him to be reared by a foster family.
When Thaddeus first displayed magical talent (through setting a bully's pants on fire), Harry collected him from his foster parents and began to train him. Thaddeus, being about 7 at the time, was initially frightened of Harry, though he did grow to accept him as his father. In addition to his training with magic, Thaddeus was instructed in swordplay (to an extent) by his father in accordance with the First Law of Magic.
His history with his mother, however, is far less fond. After pressuring his father about her, Harry revealed Hermione's identity to him. As a result, Thaddeus sought her out and was rebuked for his efforts. To this day, Thaddeus holds a spot in his heart for his mother, making the token gesture of writing a letter to her once a month or so.
Being a cordial person, Thaddeus gets along well with the vast majority of the other Mistakes, with the exception of Susan, whom he finds aggravating and obnoxious. On the flip side, he is very fond of Jezebel, both as a colleague and as a friend. Perhaps something more, but details are currently vague. As of recent events, he is Bernie's mentor in magic.
Thaddeus a bit of a studious person, though he's plenty social. He's generally polite and tries to be a pleasant person. He's also got a prideful streak a mile wide, and, to a certain extent, holds science in slight disdain.
Being classically trained, Thaddeus shows talent in many spheres of magic, with a particular taste for flashier magics, though he does have a talent for illusions and healing as well.