Millie is shortish and plumpish with brown hair and eyes. She doesn't know how old she is, but she's somewhere around 17. She can seem a bit nondescript until she pulls herself up and does her "I was a Goddess once and don't you forget it!" stance to make people pay attention. Which isn't terribly often. Oh yes, and she has a shadowy second pair of arms that she can make appear when she chooses - leftover from her days as the Living Asheth.
I've taken Millie from the time after she's left her world and her childhood position as the embodiment of the Goddess Asheth (thus 'The Living Asheth') and before she manages to get through school. She's a curious mix of tomboy and proper young lady - and still has some of the arrogance that spending all of your growing up years worshipped as a goddess will leave you with - but she's cheerful(overly), eager(overly), curious to learn about everything, very smart, and has enchantress level magical powers of her own.
Her character is from England, in a sort of Industrial Revolution with magic period in an alternate Earth history. Anything much beyond cars and electric lighting will amaze her and she may need to experiment with it till she figures out how it works. Computers will undoubtedly fascinate her. She'll probably need several.
She's independently wealthy, thanks to Mother Proudfoot managing to put 'a bit' away for her for once she stopped being the Living Asheth, so money is no issue, but she's not used to having much. She has brought with her Proudfoot, her Asheth Temple cat. Proudfoot doesn't do magic, but Asheth Temple cats are inherently magical. She's been Millie's companion since Millie escaped from Series 10 about 5 years ago. She can speak, but rarely does so.
Links to info about Millie and the Chrestomanci series:
Millie, the Living Asheth Chrestomanci series I highly recommend the books to everyone!