Board Thread:General Discussion/@comment-10674901-20130610071228/@comment-10838999-20130614085222

My Theory is that, as a Shinigami, their power if their Zanpakuto.. and their zanpakuto is basically a physical manifestation of the Shinigamis soul.

Notice however in the first couple season before ichigo reaches bankai, when ever ichigo focuses, gets angry or even when the 'old man' Zangetsu shows, his Reishi/Reiatsu and eyes turn blue, instead of red later on in the anime, I've got a feeling thats him using 'Blut' the quincy power up. notice also how Old Zangetsu looks similar to Ywatch.

Now back to the theory, a shinigamis zanpakuto is their soul, ichigo, before he became a shinigami was already a teenager who felt conflicted emotionally and with himself, this MAYBE.. MAYBE.. resulted in him having his soul or personality being split in to two PHYSICAL BEINGS when he became a shinigami as their soul is their power source, although he was already Hollofied by Aizen (or more recently the thing with Masaki being attacked by a hollow and Isshin tieing his soul to Masaki, so not sure which one is the source of Hollow Ichigo) so maybe his soul (zanpakuto).. was origionally a Quincy/Hollow hybrid (as he got quincy from his mother and hollow from either Aizens hollowfication or Masaki's attack), and Ichigo becoming a Shinigami manifested his inner confilct into TWO physical beings that is Hollow ichigo and Old man Zangetsu?

It's probably worth mentioning when he learn FGT his soul became one again as OMZ (Old Man Zangetsu) and Hollow Ichigo combine, so much like an arrancar, they regained their original form when ichigo accepted his darker side?