The absolutely sad thing is that both of these two have shown major personality issues/flaws. The stuff is sad.
If Rachel is voted out then Brendon might be able to step back and integrate into the Britney, Ragan, Kathy group. Not an alliance, but a group of somewhat viable floaters. Not to mention that Brendon can take care of himself in HOH and POV competitions. I might be underestimating things but I believe that Rachel leaving would take a huge target off of Brendon's back.
Things will remain interesting. Sooner or later the HG's are going to learn of the Brigade and then they will be on their heels. Say the Brigade is exposed, then Britney, Ragan, Kathy, and Brendon/Rachel are almost forced to align in order to combat the Brigade.