♛It’s a great question, and one that puzzled me for a long time. You have it slightly off, though.

My hair didn’t become longer after I was turned. It was wavy, almost curly, and just past shoulder length and it still is, unless I cut it. It grows back to the length it was when I died. I can’t grow a beard or mustache, however, much to my chagrin and everyone else’s relief. I would have really liked to try the kind Salvador Dali sports *laughs* Sometimes I do apply fake ones for my own amusement. Goatee, soul patch, Tony Stark-esque manscaping, it’s a hobby.

Do I have any theories on this? Well, I didn’t know it would grow back so rapidly (and completely) until my mother had cut her hair. As you may know, during the day it had grown back to the length it was when she died. At the time, after the shock wore off, we did puzzle over it, but we had no one else to compare the experience with, so we assumed it was like all of our other inexplicable physical abilities: increased speed, strength, the ability to hear thoughts. Just another piece of the mystery of what we had become.

Knowing what we know now, I would offer that our special hair growth (and the fact that it maintains the texture it had when we were alive) is part of Amel’s irrational fusion with us. 

In case you aren’t familiar with dearest Amel: we, as a species, all share a piece of the one great entity that is him, he’s our spiritual parasite. He connects us all together. 

When we give the Dark Gift, our fledgling takes an invisible piece of Amel into him/herself, and Amel gets right to work mapping out their body, unconsciously choosing the things that will work for him, discarding what won’t…

it’s a tingling feeling. Our physical appearance is important to him; he wants to preserve the beauty he finds, and part of that is hair length (this applies to all hair, all over the body… you’ll note that Jesse was groomed for it first).

For if we can remain just as we were when we died, we have the best chance of continuing to exist, feed ourselves/him, and let him experience the world vicariously through us.