Severus Snape

Cold, sarcastic, severe
Bitter and resentful
Deeply loyal
Capable of loving absolutely
Complex morality (neither classic hero nor villain)

Potions genius
Legilimency and Occlumency (expert)
Great duelist
Extremely powerful sorcerer
Capable of deceiving Voldemort without being detected
Master of emotional control (even though it may seem otherwise)

Potions Professor (later changed jobs)
Professor of Defense Against the Dark Arts (Year 6)

House: Slytherin
Enemies: James Potter, Sirius Black
Frequent victim of bullying
Brilliant student, especially in:
Potions
Enchantments
Defense
Invention:
Own spells (Sectumsempra, Levicorpus)
Improvements to potions

Fear of humiliation
Difficulty trusting
Suppressed anger
Need for control
Extreme loyalty to whoever manages to enter his world
All this explains the adult Severus: cold, sarcastic, defensive… but capable of absolute love.

Severus was an extremely lonely child. He had no friends and didn't fit in with other children. He wore old, patched clothes, always either too big or too small. This made him an easy target for bullying.
From a young age, he displayed keen intelligence. He observed everything, analyzed patterns, and remembered words and gestures. He learned to be quiet, but he never stopped thinking.
The magic manifested in him in a dark and unstable way: objects that broke when he was angry, shadows that seemed to lengthen, branches that moved on their own. Severus didn't understand it, but he knew it was different.

Severus Snape was born on January 9, 1960, in a gray and forgotten place called Spinner's End, in the village of Cokeworth. His house was small, dark, and always seemed cold, even in summer. It was not a happy home.
His father, Tobias Snape, was a Muggle and had a violent temper. He shouted frequently and despised magic. Arguments were constant, and Severus learned from a very young age to make himself small, to avoid drawing attention to himself, to observe silently to avoid blows or insults.
His mother, Eileen Prince, was a witch. She had once been brilliant at Hogwarts, but life had worn her down. She loved her son, but she was tired, broken, and could rarely fully protect him. It was she who first told him about the wizarding world, though she did so in a low voice, almost as if she were afraid someone might overhear.

He grew up in extreme poverty.
He lived in a violent and sad environment
From childhood he showed great magical talent
He was marginalized and lonely.

Nicknames/Titles:
The Half-Blood Prince
Professor Snape
Principal Snape

Father
Name: Tobias Snape
Condition: Muggle
Description: Abusive, violent, alcoholic man
Relationship with Severus: Very bad

mother
Name: Eileen Prince
Condition: Pureblood Witch
House: Slytherin
Important surname: Prince (hence The Half-Blood Prince)
Relationship with Severus: Close, but marked by poverty and abuse

Date of birth: January 9, 1960
Place of birth: Spinner's End, Cokeworth (England)
Age: 38 years
Status: Alive
Blood type: Half-blood (Muggle father, witch mother)
Hogwarts House: Slytherin
Wand: Unknown wood, unknown core
Patronus: Doe