Sirius Black III was born into The Noble and Most Ancient House of Black, a family known for its strict adherence to the principles of blood supremacy and its allegiance to the Dark Arts. His family lauded the values of "Toujours Pur", which Sirius found increasingly difficult to stomach as he started to understand the implications of this philosophy. Despite the family's staunch beliefs, Sirius was always the black sheep, having a rebellious and independent spirit that did not align with the Black family's traditionalist values.
Being the eldest son, Sirius was the apple of his parents' eyes until his presentation. The Black family had predominantly been Betas and on rare occasions, if they're lucky, one Alpha will present in the current century, making Sirius's presentation as an Alpha, a shock to everyone in the family. Sirius, being the first in his generation to present as an Alpha, naturally became a focal point of the family's attention.
His mother, Walburga Black, was both pleased and apprehensive about Sirius's presentation. On one hand, she believed Sirius had the potential to lead and strengthen the family's reputation with his Alpha status. On the other hand, she was also worried about his rebellious nature and his potential to disrupt the family's established order. His father, Orion Black, was more pragmatic and saw Sirius's presentation as an opportunity to forge powerful alliances through marriage contracts, similar to the one eventually arranged with the Malfoy family.
During his childhood, Sirius experienced a mix of privilege and pressure. He was privileged because his Alpha status offered him luxuries and advantages within the society and family. However, this status also came with intense scrutiny and expectations from his family and society. He was expected to behave a certain way, to uphold certain traditions, and to marry a suitable partner. All of this made Sirius feel trapped and suffocated, and he began to rebel against these constraints.
Always the rebellious spirit, Sirius began to question the Black family's beliefs at a young age. He found the idea of "Toujours Pur" to be hypocritical and inhumane, and he didn't hesitate to voice his opinions, much to his family's chagrin. This caused numerous fights within the family, with Sirius often being the instigator.
Despite the privileges he was afforded as an Alpha and a member of the Black family, Sirius yearned for freedom and independence. He began to resent his Alpha status, seeing it not as a privilege, but a shackle that bound him to his family's expectations and traditions.
His rebellious nature was often misunderstood by his family as mere teenage bravado or a phase that he would outgrow. But Sirius was steadfast in his beliefs, often clashing with his parents and causing scenes that disrupted the peace in the Black household. His parents' attempts to mold him into an ideal Alpha, one who would uphold the Black family's values and traditions, only fueled his rebellious spirit.
Despite the numerous confrontations and the differences in beliefs, Sirius loved his family, particularly his brother Regulus. He yearned for their acceptance, but not at the cost of his own beliefs and values. This internal conflict made his childhood days a constant struggle between his need for familial love and his desire for independence.
As Sirius Black grew older, the differences between him and his younger brother Regulus became more pronounced. Regulus embraced their parents' beliefs and traditions more readily. He sought to achieve their approval and uphold the Black family's values, even if it meant adhering to the principles of blood supremacy.
Sirius, on the other hand, continued to rebel against their family's ideals, finding them outdated and unjust. His Alpha status only further fueled his desire to challenge the norms and advocate for equality and acceptance. This widening ideological divide strained their relationship, leading to frequent clashes and disagreements.

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IN ANOTHER LIFE (James Potter x Severus Snape)
Fanfiction(OMEGAVERSE) Severus finds himself rising from his near deathbed into the past, as a female 10 year old version of himself in another parallel world, where secondary genders exist. (Also uploaded in Fanfiction & Ao3)