Ichigo's Hollow and Kaien's Hollow are too dissimilar to be related at all. Different masks, powers, voices, etc. I think the two have nothing to do with eachother. The Hollow we have seen in Ichigo seems to have been created as his chain was being eaten away (this is how Hollows come in to existence). Also, Kaien's full name is "Shiba Kaien"Originally posted by: masamuneehs
And, as for the almost-Hollow incident in Urahara's Training Pit, I believe that was a manifestation of Ichigo's Hollow nature (already in him from Kaien) trying to take over, but the Shinigami part won out because Ichigo is a "good/positive spirit" and not a negative/Hollowish spirit. I just think it was the first time that the Hollow nature tried to take advantage of Ichigo's weakness/shortcoming.
I listed plenty of evidence in the episode discussion, but I'm honestly too tired to copy and paste it all. If you still need proof though, I'll do it when I get back.Originally posted by: el_boss
With that logic you might as well say that there is no evidence for your theory (number 1)
Kraco and Frogking, I'm starting to consider theory number 6. That one makes very good sense, and I wouldn't be suprised if the truth were something along those lines.