It's not just OPs strange and mysterious predicament that has made this thread epic, but also the genuine efforts of some of us to help OP in the midst of wild, off the wall, guessing.
And then there's the misplaced reply that ended up in the perfect place.
That's something that, depending on your POV (sadistic DM or a player), might be either interesting, or really terrible.
But then again, it takes time (to know that you're fucked) so I guess it's just horrifying. You'd never know if you've fucked yourself up using the power.
The 2003 FMA anime was created back when the manga is still being published, and started to drift away from the manga such that at the anime's midway point, it's following a different storyline. Some plot points and characters are changed as the anime overtook the manga. Ultimately, it's a different story as opposed to the manga and Brotherhood.
However, I like how the pacing is a lot slower, allowing me to get more invested and interested into the characters. It's not as fast-paced as Brotherhood, and it's a lot darker. There's just something really somber about the entire thing that I can't put my finger on.
I watched it on cable TV back then, but I think there are some sites still carrying it if you know where to look.
As for One Piece, thanks for the advice! I'll go do just that once I have the time (to watch the first half--or I can just go full manga). I don't think you're proselytizing than you're just excited to talk about something you're really into, which is nice.
And yeah, the only thing stopping me from watching One Piece is the sheer amount of episodes, lol! I want to start watching it, but I'm like, there's no way I'd be able to watch thousands of episodes just to catch up!
Meanwhile, I was thinking more along the lines of FMA's law of equivalent exchange, but since the way equivalent exchange is handled is kinda hand-wavy, I tried to find a way to make it more realistic, while trying to limit the power's OP potential (hence, the random body part stipulation as initially stated).
TBH, I don't watch One Piece, but had I done so, I would have given you a nod by saying you need to be concentrating to use the power (and would backfire by randomizing the target of the power if you lost concentration).
I mean, yes! But I don't really think ordinary object manipulation (like what we can already do IRL) counts as using the superpower.
The way I see it, it applies to things like telekinesis, or manipulating the mass of an object (making things lighter, or heavier), or even something as out of the left field as "manipulating gravitational lensing such that I can see things clearly". It can even be used in such a way that it can be lethal, such as "make someone's blood dense, and have them suffer a heart attack as a result."
The superpower is actually that OP in the sense that aside from the limits I've put (and the modifications we've agreed upon), only one's imagination is the limit.
I mean, that'd still make it somewhat OP, I think.
Though to be honest, your approach is similar to what I actually came up with as a consequence for a different superpower (time-space manipulation--which I think is a lot more energy-intensive), in the sense that it'd take energy from the least important part of the body to the most important.
However, I suppose just having the energy requirements already limits a lot of the OP potential of the superpower (can't just summon a black hole, lol!), so I think your changes are quite reasonable.
I wasn't really thinking much about it, tbh, but it's more along the lines of "cell burns glucose to create energy", or "random photon hits skin cell, making it slightly warmer," or in the more unfortunate circumstances where the random part of the body is, say, a brain cell, it could have not much choice but to "spontaneously undergo nuclear fission."
It's me trying to cover my ass, tbh, and make things more interesting by just not going "E=MC² thus things go boom!"
I suppose you can go use the power safely most of the time, but there's a chance that something important might go off in the most unfortunate way.
Cool! Every time you manipulate gravity, your body loses mass in addition to and proportional to how much energy is needed to do the manipulation.
Which part of your body loses this (additional) mass is totally random. It could be your fat, it could be your brain tissue, it's all random. How the mass is lost depends on what is the most likely way it'd be dissipated.
Not just the architecture, but also the possible logistics of such an event. Who'd contact John Oliver's PR team, for example. What about the scheduling? Also, while I think people here are good-natured enough that it might not be necessary, who'd be making sure that the thread responses (the questions) don't violate any community and instance rules?
I may be overthinking it, but such a huge event would involve a lot of coordination from many different people.