Changelings - The Rules and Guidelines

Trinity here, finally! I've been sick, and that is my excuse for not posting, but I'm getting better, so hopefully more posts are on the way. (Hannah's been doing a marvelous job keeping the blog up-to-date and fabulous in my absence, by the way.)
Recently I've been pondering and reasoning about my changeling characters. I decided to be ambiguous on where exactly they got their powers, at least for now, and just focus on how they work.
So, Rules and Guidelines For Changelings in Trinity's Yet-To-Be-Named World.

1. Changing takes energy and concentration. 
It is very difficult for a changeling to complete a change when tired, running, frightened, distracted, or basically under any sort of duress.

2. Emotions affect the speed of a change.
Depending on the changeling, being happy could speed up the changing process, while being sad could make it take longer.

3. While in changed form the instincts of the true form will be present and must be suppressed in order to perform actions inconsistent to the form's nature.
For example, if a changeling became a cat and had to cross a river, they would have to suppress the cat's distaste for swimming and water in general. A changeling is able to fully distinguish between their own thoughts and the urges of the animal when in a changed form.

4. Every changeling has a Familiar.
A familiar is the animal form they find easiest to change to, easiest to control, and usually matches their personality the closest. Every changeling has a familiar, though sometimes it can take years to discover what creature it is. Each changeling must find their familiar for themselves, as no one else can tell what your familiar is.

5. A changeling's familiar can change over the course of their lifespan.
If you've read or watched Harry Potter, you will be familiar with a "patronus". (That is, a positive energy force that is fully-formed, taking the shape of bright-white, translucent animal. The specific animal forms that corporeal Patronuses take vary from person to person and reflect each individual's personality). Now, you have to have read the books to know that a person's patronus can change based on events that have changed their life. Similarly, a changelings familiar can change, though it's very rare.

6. When a changeling is exhausted, or greatly distracted, they may not be able to complete a change, leaving them stuck in what's called a half-change.
Half-changes are unnatural and unsafe. During this time, a changeling is unable to clearly distinguish between their human thoughts and the animal's urges and instincts. It effectively scrambles the human and animal "brains". It will also affect mobility as neither "brain" is used to the blended proportions, though theoretically this could be overcome with practice, it's highly discouraged and deeply frowned upon.
There are several ways to recover from a half-change. If distracted, resume your concentration and complete the change. If exhausted, rest and/or eat and then complete the change as soon as you possibly can. There are herbs that can help complete a change, but they're difficult to find.
In general, accidental half-changes are harmless, but there is at least one recorded incident when a woman who remained in a half-change for over a month eventually went insane.

7. A half-change from one animal to another is the most dangerous of all.
This is because you now have three different "brains" vying for control, thought still only two sets of proportions. If a changeling has any doubt at all that they will not be able to complete the change from one form to another, they should not attempt it.

8. Any injuries a changeling sustains will translate over to another form as anatomically closely as possible.
For example, if a changeling was in cat form and lost their tail, say, because it got shut in a door, when they changed back, their human form would likely have a gaping wound on their lower back.

9. Each changeling has their own size limit concerning changes.
This limit can be stretched/pushed with practice. For instance, when a changeling first begins to change, they may only be able to change into an animal the size of a mouse, but can work up to chicken, then a cat, then a dog, then a goat, and so on and so forth.
Some changelings who have larger familiars may have more trouble discovering them, as they first have to reach the size group of their familiar. For this reason also, some changelings never find their familiar.

10. Every change a changeling makes leaves it's mark on the changeling.
An example would be, that if a changelings last change was a snake, their movements may tend to zig-zag a little, they may be a little more slender, their hair color may change depending on the species of snake, and they may tend toward using words with more hissing noises.
Usually the effects fade the longer a changeling is in their human (natural) form. However, the longer a changeling spends in a specific form, the more permanent the effects from that form become.

And that's all I have for now in the way of my changeling rules and whatnot. If I think of anything else, I may do another post on it, but then again, I may not. We'll see.
Also, I do plan to put more Tribes of the Earth up, but it might be a little while since I need to edit it, and Christmas is coming up, and all that good stuff. So, yeah. I'm procrastinating. I also have a character post in the works, and that'll probably be my next post.
Anyhow, it's getting late and I must be off!

Sé onr sverdar sitja hvass! 
~ Trinity