A/N:Hi! I'm Crystal Tempest and this is my theory on how Steven's ability to poof. I have a fanfic in the works on this called Poofing: A New gem sort of rises. R&R!
So,to lay all the cards out on the table,Rose isn't an option. The videos show her will for him to live,so she would stay as a guide,but would keep herself from reforming out of
her love for him. Next, when looking at other poofed theories and fanfics, They've come upon the same problem. What about his organic body? I've made answer that uses science to solve it.
Separation. if his body were to be hurt enough to warrant poofing,or death ,his organic self and gem would separate as a survival tactic. The body does often separate somethings out of survival,so it's possible. It also takes care of what would happen,as Steven's body couldn't fit in his gem. Basically, he would reform and his organic self would be lying there dead next to him. From there,the only solution I can see,is going to Bismuth's forge and cremating his organic form,or sending it to home world claiming Rose Quartz dead. But the latter isn't very likely. From there,there are a vast amount of possibilities that could happen. I might write about a couple of them.
Next,as it has come to my attention,how would Steven act if he cracked? i think he would grow his own symptoms and issues because if he wasn't a regular gem,he's not going to have regular symptoms. If he was a full gem as possible through the theory above,he would act much like Amethyst,perhaps a similar reaction than that of when he went against anti-gem weaponry in the episode Jailbreak,or it might be like getting shocked at high voltage and the after effects of that. If he were to develop his own in his human form,I believe it would be something like random language switches,projectile vomiting,and seizures.(might do a fanfic on it)
Finally(For now), We have what would happen if Steven shattered? In his gem form,it would be like regular gem shattering,but in his human form,it would be death. I believe he would have either the shards kill him,or it would be an energy issue. From what I've seen from regular episodes,while Steven loves food,he only really eats one or two meals a day. But is filled with energy somehow. Also,how did he survive in the episode bubbled? The answer? He's pulling energy from his gem. This may have started when he was very young, with Greg's forgetfulness. Steven does it to survive. So much,it's automatic. So much,that if he suddenly didn't have the energy,his body would crave it and NEED it. He would have bits of energy,but imagine the energy it takes to power Steven as an electric train.(Like the bullet trains in Japan trains) Now the energy he gets from Food and sleep is one hundred double A batteries. It's not going to able to power everything. Then,Imagine with me,his gem is like a giant power plant. The power plant is going to be the main source for the train. So if his gem is shattered,the power plant is blown up essentially meaning that no amount of AA batteries can keep the train running. Based on that,he would then die after a day maybe,of painful agony. (Might do a fic on this as well).
I'll add more as I think of them.