Prologue
Edward was too young to remember anything, and Trisha was only eight months pregnant with Al at the time, when she went away. The eldest child was taken by her father the day she turned six and was never heard from since.
Trisha tried to put it all behind her. She knew that taking her away was for the best of the family and for daughter's own safety. Ever since she could walk, she was able to do alchemy, just like her father. So, Trisha did what she had to do. Everything about her was to be forgotten; her siblings are to never know they had a sister. Every single thing in the house that reminded anyone about her was to be locked away under a key and disposed of. Hohenheim was right to do that.
So that's what she did. But she didn't get rid of it. No… she kept it all under lock and key. The metal box with her special rose kept safe inside was buried in the ground outside of the house. Deep down so no one would find it, or at least as deep as she could manage being pregnant and all.
She promised not to tell her sons anything about this. But she couldn't help but leave clues for them to find out. After all, Ed was going to watch out for Al, but who was going to look out for Ed when Al wasn't around? The only thing agreed upon was that she could contact Pinako, and only Pinako. And she promised to keep it a secret, as did Winry when she grew up.