I think I know. Once I've done their loyalty mission and do the post-mission discussion about that, every character then gives a "let's talk later" response. I had assumed that this was the end of their character arcs. I actually talk to them quite a bit.
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Yoblazer: http://oi42.tinypic.com/15douf9.jpg
Watch and you'll see... SuperNiceDog own me... in the Guru!