Tyrannus "Baz" Basilton Grimm-Pitch (a sweet cinnamon roll who needs protection) was born sometime in 1998 as the son of late Natasha Grimm-Pitch and Mr. Grimm. As a young child, he watched his mother get killed by vampires, becoming one himself on the same day.
"I don't specifically remember going there on the twelfth of August. But I do remember when the vampires broke down the door. Vampires - we - are unusually strong when we're on the hunt.
"I can't tell you how many vampires came to the nursery
''gay rights'' -basilton grimm-pitch

that day. It seemed like dozens, but that can't be right, because I was the only child who was bitten.
"The way I remember it, my mother was right behind them, there almost immediately. I could hear her shouting spells before I saw her. I saw her blue fire before I saw her face.
"She shot streams of fire over the children's heads; the air was alive with it. I remember the look on my mother's face when she saw me, a flash of agony before the man holding me sank his teeth into my neck,
"And the pain.
"And then nothing."

~Baz's POV during the vampire attack Edit

He began attending Watford in 2009. The Crucible drew him and Simon Snow together as roommates. They hated each other almost immediately. He also became friends with Dev and Niall.

Baz began to have romantic feelings towards Simon in his second year, but became more obsessed in fifth year. In the beginning of his and Simon's last year, Baz didn't show up for 6 weeks. Simon obsessed over Baz, anxiously questioning what he could be doing, and if he was okay.

As soon as Baz came back, he tells the reader that he was captured by numpties. In his POV, he tells us what he did to stay alive and sane. This was the first time it was proved exactly how Baz felt about Simon.

"And when I felt myself slipping too far, I held on to the one thing I’m always sure of - 
"Blue eyes.
"Bronze curls.
"The fact that Simon Snow is the most powerful magician alive. That nothing can hurt him, not even me.
"That Simon Snow is alive.
"And I'm hopelessly in love with him"

~Baz recalling how he survived in the coffin Edit

Baz later burned down a forest, having full intentions to go down with it. Simon followed him into the flames and stoped the suicide attempt by kissing Baz. They also kissed several times later.

Simon eventually had to go back to Watford to defeat the Humdrum. He lost all of his magic to defeat the Mage, his father, all the while gaining a tail and wings. Baz comforts Simon as best he can, and reassures his love is still strong, even though Simon isn't the Chosen One.