Brian was born to a completely normal family in a completely normal neighborhood of Cambridge. The only son of a professor and his wife, from a very early age learning and scholastic excellence were the foundation on which Brian's life was built. He took to it well, which was, perhaps, fortunate, as his parents would not have known what to do with a child who did not see the acquisition of knowledge as important.
It wasn't until he started school officially (his parents had begun to tutor him long before he was of age to attend) that Brian's personality and preferences began to develop and broaden outside of those provided by his parents. He still loved to learn, but soon found he also excelled at sports, a pastime at which his father in particular scoffed. His world became less cerebral and a bit more physical. Less theoretical and more practical. Knowledge, he decided, was always good. But knowledge coupled with firsthand experience was better.
Brian was eight when … odd things … began happening. That was the year a quiet, gentle friend of his, named Charlie, was being bullied by an older boy several years ahead of both Brian and Charlie. Lacking the size or knowhow to retaliate physically, or in any other way, Brian swiftly became more and more agitated about the situation. At first, things like lights flickering and small objects rattling could be explained away. A loss of power, children racing past and jostling things. But after a while, Brian started having difficulty explaining them away, and wondered what was going on. Still, he did not even begin to connect the incidents with his own emotional state at the time. Before things could come to a head, summer break arrived.
The next year, when school started, things had died down. The bully had moved on to other prey, and Brian had no reason to get as angry as he had in the latter half of the previous school year. The odd happenings ceased, and Brian eventually forgot about them. Until the next year. Ten years old, and a new school bully on the loose, this one not content to resort to hurtful words alone. Just a month into the school year, Charlie was beat up. Brian wasn't there at the time, but he was outraged. Older, stronger, and with more knowledge than two years previously, he tangled with the bully on several occasions, coming to the defense of those unable to defend themselves. The two boys quickly became locked in a battle of wills, wits, and physical intimidation. Mostly, Brian won in the wits arena, which kept him /out/ of the physical one. He was too smart to allow the bully to corner him.
But when the bully targeted Charlie, things started getting weird again … and quickly. And it was stronger this time. Lights didn't just flicker, they /blinked/, staying off for a second or two before coming back on. Small things shook themselves right off of whatever they were sitting on, and larger things (mostly student desks) rattled, which hadn't happened the first time 'round. It scared the crap out of Brian, but that only made things worse. It started happening at home, though not as strongly as it did at school. Then, in late March, Charlie got attacked by the bully again … and this time, Brian was close enough to arrive on the scene mid-fight. The next thing anyone knew, the bully had been knocked a good ten feet back … without ever being touched.
The very next day, the family had a very … odd … visitor. A visitor that explained what was going on … and opened the door to a world that neither Brian nor his parents had ever dreamed existed. Brian's parents were torn between utter fascination and squirming unease. Brian was just relieved that there was an explanation for what had been happening.
Brian finished out the year with private tutors, and made his first trip to Diagon Alley a week after he'd been informed he was a Wizard, to get some books and find out about the world he'd be living in. He found it bewildering, confusing, and fascinating by turns.
As bewildering as Diagon Alley and the available information on the wizarding world was, Hogwarts was ten times worse. Brian was surprised to be sorted into Gryffindor … he'd been expecting Ravenclaw, given their bent towards scholarly pursuits (at least, as he understood it at the time). He spent most of that first year perpetually confused and lagging behind his yearmates in his studies.
Brian finally caught his stride in his second year, having finally become at least somewhat accustomed to the magical world. He began to make friends, not just in Gryffindor, but in Ravenclaw and Hufflepuff as well. Slytherins he could not abide at all. They all sneered and strutted about with airs, and were generally sneaky, underhanded bullies and gits. That he was Muggleborn, and therefore a particular object of Slytherin scorn, didn't help matters.
His footing found, he began to excel scholastically again. He consistently did well in his classes, but particularly in DADA, and began to contemplate the possibility of becoming an Auror when the time came. The rumors that flew on a near-daily basis from his second year on only strengthened his resolve to achieve that goal. If Voldemort /did/ return, Aurors were going to be needed. Badly.