Sorry I didn't get in a post when expected, guys, I have some stuff IRL that I've been involved in that's been taking up more of my time than usual. It will probably be finished in a few days, though, so I can RP more effectively.

As for this new character, guys, it's probably a new student, since it would be more likely for people to mix up regarding her age if they had never seen her before. Additionally, I intend to add balancing out for her powers, but I don't know when I'll get around to making her. I typically don't want too many characters, and the idea for this one's powers is highly abstract, so it may or may not work out, to begin with. I can give you a general idea of the powers, though.

The idea behind her powers being linked to an alternate dimensions involves the concept that some dimensions are more 'removed' from the world than others. She isn't fading into a weird, alien dimension, but a 'shadow' dimension that overlaps our own very closely, almost like some concepts of a spirit or dream realm with slightly alternate laws, and happens to be almost identical. This is how I explain it, with the additional claim that certain actions will generally affect it; while others don't.

 Something like light or photons or just energy, which are generated by anything light or electricity-related, do not typically consist of atomic matter, and can penetrate into this dimension, meaning if you have a power involving lasers or any other ridiculous amount of light, you could possibly still affect her; though physical powers, bullets, or anything else physical won't work; it's just like how I would see a ghost if it weren't involved with magic. Physical beings, like humans or animals, will appear as ghosts in this dimension, sort of like transparent phantoms, which is how this character knows where they are; these phantom images, however, do not make noise or any tell-tale signs that would let you know that something was coming, similar to how my character is almost always going to be a bit phantom-ish, so she normally does not produce sound unless she wants to. The reason for the character being able to become intangible is that in this dimension, she kind of happens to be so lacking in density normally that she can pass through things without much difficulty, and her powers allow her to retain her vitals and such without losing order or stability (Although definitely, it would kill her to lose intangibility inside solid matter, it's a guaranteed way to die). This in mind, though, she could accidentally float up into the air if she isn't careful, so she actually has to concentrate on the ability to maintain friction between herself and the ground; it's a conscious effort to do everything in this dimension, even being tethered in it. I will also give her the breath limitations. She's mastered these aspects of her powers by the time she reaches the school.

Powers I want to leave for development is that she could actually figure out on an advanced level, with practice, how to control her floating, not just by how high or low she is based on friction; but how to actually control directions, too, since 'floating' isn't really 'flying' if you can't go anywhere and you're floundering in one spot. Additionally, since breathing is something that usually has limits, I want to say she has greater lung capacity than most people, even for her small size (Since super-limited lung capacity would ruin the benefits of her power pretty badly), enough to actually rival perhaps a professional diver; however, her lungs won't be expanded to this limit, because she's never tried to stretch how long she's been in the dimension. The maximum time she could hold her breath would be based on that of the capability of regular humans, since it's possible for an impressive amount of time; there will be lots of passing out, though, from not enough oxygen, before she ever reaches the potential, she might never reach it, who knows?

Anyway, those are my ideas.