Board Thread:Theories and Speculation/@comment-26127155-20150608044937/@comment-945885-20150609080847

My current working theory is that Shin Uchiha provided the Akatsuki with medical support at some point in the past, and he obviously has a connection with Itachi. Beyond that it's really hard to guess how he fits into the group.

The more he talks, however, the more obvious it seems to me that he's a completely new character. His motivation seems to be tied into the idea that humans evolve and improve themselves through war, and he has obviously surgically modified his own body. His "sons" are likely clones he's cultivated and raised, as he's quite willing to sacrifice them to protect himself and harvest their organs to replace his own.