By the time we get to "Pain" it looks like Volker's going to endure something rather...interesting and violent. This link
shows some production notes about "Pain." Now this page reveals virtually none of the plot information so nobody really knows the specifics of what's supposed to happen, but if you look at the final two bulleted items in the production notes, you get this:
"Gold star for @PatrickGilmore today. Great, creepy, unsettling work." — Carl Binder, Twitter (September 10, 2009)
"Thanks to @cpbinder for the 'Pain' & the gold star. Crazy last day of the episode. Bruised forehead & an exciting #SGU episode to prove it." — Patrick Gilmore, Twitter (September 10, 2009)
Words like "creepy" and "unsettling" are definitely words that I would never associate with the Volker we know right now. The fact that he ends up with a bruised forehead at the end of "Pain" and the way his performance is described says something.