I’ll admit that was unexpected. Actually when I started reading this I wasn’t even sure if the main character was Sirius or Severus. Of course, that part became clear when he was upset by the death of James. I’m not sure Severus wouldn’t have smirked, assuming even he could smirk so soon after Lily’s death.

Anyway, moving on. When the child showed up I naturally thought it was Harry. I was all prepared to go into former!mod mode and talk about how Harry was an infant in a crib. He wasn’t walking or talking. But then it wasn’t Harry. It was a girl. New siblings often pop up in fan fiction. Severus has had a sister. I love giving Lucius a sister, myself. Once I even read about a fourth Black sister, but I can’t imagine that one. With the ability those three have to get themselves is awful situations a new addition seems entirely unnecessary. But I’ve never thought about there being another Potter out there, well at least not from that generation. Maybe a sister for James.

I like this idea, and I like that Sirius took her away from everything, erasing her memories and giving her a chance to grow-up without the insanity. However, I don’t understand why he’d do this for a sibling, but not Harry. I also don’t understand why Dumbledore never tried to track down this child. Actually, maybe I do. Harry was the Chosen One, not her.

This is a very intriguing start to your fic. I think it has great potential. I look forward to reading more. Good job.