The lab was dark. Irene Adler watched her new creation grow and divide.
"Soon, my lovely. Soon you will grow and grow and be so smart and pretty just like mummy and daddy."
She looked at the photograph of Sherlock hanging on the wall by a thumbtack.
"You will be mummy's little weapon, won't you? Mummy's beautiful little weapon. Won't that be splendid! You'll be my new security. You'll be The Girl."
She glanced lovingly at the petri dish, soon to be her daughter. It would have to be a girl. Irene needs to pass on her figure.
This security is vital. She knows it's only a matter of time before Sherlock has her former security. That's why the accelerated growth serum is necessary. She obtained it from one of her many clients.
Irene fills an eye dropper with the liquid and drips several drops slowly into the cells that will one day be her protection. Her weapon. Her daughter; her girl. Three years of growth and development for every one human year, until she reached the physical age of 18, that sooner the better.
She smirks imagining Sherlock's reaction if he were to discover her newest project. It would probably turn his brain off, send his Mind Palace scrambling for cover. That's how Irene likes him; docile as when she injected him with the sedative for her protection. Always for her protection.
That's how she managed to get hold of some of Sherlock Holmes's precious DNA. After that it was relatively simple. Combine it with some of hers. Add growth serum. It's a bit like a middle school science project, only the product of the experiment isn't a participation award, it's deadly. It was just too perfect.
She set the petri dish down and shivered with excitement. In just three months time, she would be a mother and Sherlock, her dear, wonderful, terrible, heartbreaking Sherlock, would be a father, just like she always planned.