Replying...
Intro. 1. Prioritizing your own daughter Many fan scenarios discuss that if Sirius had a daughter of his own, he would put her well-being above Harry's adventures. Not a "James Replacement": Instead of pushing Harry into risky situations (like he does in Order of the Phoenix), he would be more careful. He would see Harry more as "his daughter's best friend" and treat him like a nephew, while his daughter would be his absolute priority. Emotional Presence: He would try to make up for the lost years from Azkaban with his daughter. This could lead to him loving Harry, but setting clear boundaries for him so as not to neglect his daughter. 2. A new family dynamic in Grimmauld Place The house at 12 Grimmauld Place would not be a place of depression, but a place of rebellion for his daughter. Protection from Black Heritage: Sirius would be extremely careful that his daughter not be influenced by his family's dark traditions.

Sirius Black & His Daughter (Without Sirius' Death)

@Arianna