Hmm... there are a few problems with this.
So right now, the bad parts of Sasha I know about are that she is kinda klepto and has recently obtained a joy from both fighting and possibly killing. She is also irresponsible, lazy, and has a possible hero complex.
That being said, you want it to inherit all of those bad traits and none of her good traits. While under normal circumstances that may not be so bad, it actually is, especially if you don't want it to inherit any humanity.
This is why some people have a hard time mastering Soul Familiars when they inherit bad traits that would make them disobey. If you make it inherit all of those bad traits and no humanity, you will just create a feral, dark side version of Sasha who probably will resist obeying Sasha's commands and, thanks to Sasha's recently obtained joy in fighting and killing, may possibly try to attack either Sasha or those around her, showing no regard for friend or foe.
Now that being said, you can still go with this. Or you can try something else. It would be interesting story wise (as this and its appearance as creating a girly cross dressing boy from your psyche may require you to reevaluate yourself), but in terms of usability...
There wouldn't be too much.
This is just a warning, cause I am not that much of a dick to give you something, have you make a bad choice with it, and then make that something useless without a bit of a heads up if its something that you couldn't avoid due to not knowing anything about it.