Below, you'll see any text that was highlighted with comments from the reviewer.
Message to Readers
My brain: don't start another project. you haven't finished your four other ones
Me: *starts another project* .-.
My brain: *facepalm*
Prologues are the mildly to super mysterious intros to stories that either whack you upside the head with a shocking happenstance you barely understand, or begin the story with just enough background information to get you real interested in it, or somewhere in between, of course. I think this prologue really gave me great background information--introduction to Sam the witch, the Mouse, their basic personalities and attributes, what they're doing... I really like the idea of a lonely witch adopting this boy, who seems to have a tough past to him. It seems like the start to something magical! I get the feeling of starting too many projects. I'm always starting ideas of new novels and writing beginning chapters and abandoning them. I think this story would be amazing if you continued to expand on it. Don't abandon it like I've done with so many scraps! However, if you feel like you have way too many projects on your hands and you want to work on them first, I suggest you could stow this away for a bit and ruminate on it while you write the others. ^-^
Considering this is a prologue, and it's supposed to be mysterious to pique readers' interest and curiosity, I don't think you really have to add any more details to it.
I really enjoyed reading this piece! I'm not the best at titles, but I think "The Witch and the Mouse", though generic, keeps up the nice fairytale vibe you have going throughout the story. If not, maybe consider the overall plot of the story to come and pick out a great, catchy title from there. An example would be Phillip Pullman's series His Dark Materials. The first book of the series is called Northern Lights, cos those play a huge, magical role in the book, and it sounds really nice.
Just remember that it's alright if you can't think up a title immediately.
In conclusion, keep up the awesome writing, and I wish you all the best with your projects. :3