For any of those that like the anime/manga Bleach, here's a little food for thought. A theory I have come up about Ichigo and his state of being overpowered as a Human-Shinigami-Hollow-Vaizard-Arrancar-Fullbringer-Quincy.:

First of all, Aizen's been experimenting with hollows and shinigami, making vaizards and arrancars, we all know that. And obviously, he had access to Kaien from inside that one hollow, hence Aaroniero Arruruerie. So let this fester in your mind for a moment... Perhaps that black hollow that looks like Ichigo's hollow form WAS Kaien? Aizen having taken Kaien out of that hollow. Perhaps Ichigo is a direct reincarnation of Kaien. When his mother allowed the hollow to stab her so that she could shoot it in the neck, Aizen had the thing transpose it's self inside of her, waiting for the other half, Isshin, to supply what is needed for life. That right there explains the shinigami, hollow, quincy and human components of Ichigo. But then, how can he become an arrancar and a vaizard at the same time? That's easy. Being a medium for powers of all kind, that explains how Rukia was able to give Ichigo her powers, powers that aren't his. This also explains why Ichigo's Zangetsu looks like Isshin's Engetsu, rather than Kaien's zanpakuto. There wasn't as much shinigami in the vasto lorde that attacked his mother, so that's why it was vital for Isshin to be the father, to reinforce the shinigami component. As we al know, arrancars were hollow turned shinigami, as vaizards are shinigamis turned hollow. It's no secret why Ichigo was able to become both. When Byakuya severed the soul chain and the other component I can't remember the name of, he "lost" his powers. When he was being helped by Urahara, he was turning hollow when he got his own shinigami powers(which were actually his dad's, also explains why Isshin's not part of the 13 court guard squads anymore, he's not strong enough, from losing his powers). So he didn't become any one of them first. It was a duality almost simultaneously. And then he was supposed to lose his powers with the final getsuga... Yet technically that would ONLY mean the shinigami powers, since it IS a zanpakuto ability. Meaning he would retain his hollow powers, meaning the hollow form and the vaizard mask, he would just lose Zangetsu. But he lost all of it because hollow ichigo fused with zangetsu. Why would this be? Because Zangetsu isn't soul. Zangetsu IS that black hollow, an experiment of Aizen's. So taking that into consideration, and the fact that Aizen was impressed by Isshin... The hollow copied Engetsu, resulting in Ichigo's powers being a carbon copy of Isshin's. And then, after all of that, losing all his powers and what not, how did Ichigo get them back? Fullbring, but that's a unique human ability that wasn't exactly supposed to be taught, just unlocked in those certain individuals. Which goes back to Ichigo being a medium for power, the one thing Aizen strived for. Guided by Aizen's experimental hand, Ichigo's ability to gain more power allows him to draw forth his OWN power that was left in the badge. With his powers being that huge, there was enough in the badge to sustain a similar, weaker form that Ginjou ended up stealing. So then what else happened? Urahara had that sword that everyone transposed their reiatsu in to "reawaken" Ichigo's shinigami powers. But why didn't they do that for Isshin? Rukia? Because it's impossible. They lost their powers due to a weakening of their souls. How was it then, possible for Urahara to revive(Yes, revive, not reawaken) Ichigo's? It's simple he was bringing back "Zangetsu" who wasn't REALLY Ichigo's soul. He was an entirely separate being that grew accustomed to Ichigo. So once stabbed with that special sword, which I believe was the empty conduit of Zangetsu, the blank beings that would become a shinigami's zanpakuto made by Ouetsu Nimaiya. Taking powers from the Captains, using the ability transposed by Aizen to basically leech for power, revived the being Aizen initially created, which was that black hollow.

And as another little thought to allow to fester, this would also mean that Ichigo COULD become a Bounto, if it had been cannon in the manga.