I did see the "Work in Progress," but usually there are places left blank if it is as such. And since the Background wasn't left blank I simply assumed that it was finished. Apologise for that, but it looked finished since everything was filled out, though some of it being a bit bare.
As for the poison/Flame thing. There are myths of the manticore breathing fire, and of it being poisonous. It's both so you have free reign as to which one you choose. I only ever mentioned flame because it's a possibility.
As for the size. As a Demon I imagine he'd be a bit larger than a tiger. perhaps 20-50% larger in total. He'd be one of the slower types of Demons, having far more defense and physical strength than others, but still be plenty fast to outrun a Titan.
As a Titan he would be much larger, perhaps 2/3 the size of the average Dragon. Faster and more nimble than the average Titan, but a bit lacking in raw power and defense, making up for that with his poisonous spines/thingies he shoots from his tail.
You complain a bit about how he'd be weak and small compared to dragons who can crush him with a foot, so here's a few human/dragon comparisons of what I view is their average size:
Dragons are the #1 of the Shifters, and unquestioningly the most powerful of the all, but that doesn't mean that you can't beat them. Each and every Shifter has strengths and weaknesses, and while the Dragons are the most powerful they are not quite as quick as the Demons, and despite their immense power and defense, a Fae could still blast them into next week. It's not only about size, but speed and agility. Sure someone may be huge, but who's to say they can land a hit on someone who's smaller and much faster? It's also not 1v1 fights, but group skirmishes or even small wars between a couple hundred shifters. So he's never alone, and he always has dragons or other massive Titans to take care of the opponent massive titans.
I also can't help but feel that, judging by what you just wrote, you're making a self-insert. That is, essentially putting your own personality into a character and then playing that. I advise against that, simply because it hints at a lack of writing skills. I know that sounds harsh, but that's really what a Self-Insert tells me :/ Regardless, that kind of character is not someone I'm sure would be accepted into the Academy. If he's likely to punch someone because he doesn't like them, then he does not fit in with a group of soldiers. They can't give him special treatment and group him with people that he likes just because he'll punch anyone else.
As for the unit thing. It just does not fit in with the mythos. A Manticore does not have some magic that suddenly makes him able to run faster. He has whatever speed his legs and such gives him. He is, essentially, magic-less, as is many Titans and other Beast-like Shifters.
and that the Manticore I made up is very different.
No. Just don't. This is not something you "make up." This is an RP centered around magic, and every other character here has their powers from mythology itself. The only exception might be our Giant with his touch-based telekinesis, but that's pretty much equivalent to brute strength and nothing more. So yes, I expect people to stick to the actual mythology as much as possible, making changes where it's necessary to give it some semblance of balance.
I know I'm jumping a bit back and forth here, but:
Manticore and dryads and other creatures like that aren't really meant to go beat up dragons or giants.
Indeed, they're not. While a Dryad alone would be able to restrain a Dragon, they do not quite have the raw power to kill them. That's why you
work together like actual soldiers and comrades.