I know this topic hasn't been posted in for a while, but I've always wanted to express my opinion on this matter so I hope nobody minds.
Before I go any further, I want to say that I'm not a fan of Rachel - at all. And I go back and forth with Brooke but in a general sense, like her character. Having said that...
What exactly did Rachel do to Brooke that warrants such a heinous act from Brooke that Brooke didnt also do to Rachel? Both girls were catty with one another but Brooke did start it. She hated Rachel from the beginning with no true justification. Brooke pushed Lucas into a nonexclusive relationship and then had the nerve to get all whiny and bitchy about it. Yeah, okay. Rachel was definitely annoying during the process but she technically didn't do anything wrong. Lucas was single - by Brooke's definition.
The whole cheerleading thing...please, what was such a big deal about that? So Brooke now had to deal with a little inner competition. Oh, the horror. Was it catty of Rachel? Yes, but does that situation justify publically humiliating someone based on their physical appearance? Hardly.
Then we have the "fantasy boy draft" incident. Rachel may have manipulated Bevin into trading spots but Brooke STILL would have been before either girls. Brooke was petty and chose Chris to stick it to Rachel when she had ample opportunity to choose Lucas. She should have paused long enough to ask herself why she was more interested in messing with Rachel as opposed to picking the boy she loved. Hmm... So again, Brooke's fault. And what happened between Lucas and Rachel at the Rivercourt was insignificant considering, by Brooke's rules, he was single. And he turned Rachel down either way.
Rogue Vogue comes next. Rachel, however selfish her reasons were, actually did Brooke a favor. This was a major opportunity for Brooke and it was her choice whether or not to take it. Who cares why Rachel did it? The reasons still don't justify the whole public humiliation thing.
The biggest argument I've seen in this thread is the whole time capsul incident and Rachel's involvement. Okay, that was a terrible thing she did and it was a catalyst to the school shooting but I honestly don't put that blame on Rachel. Many things can trigger someone to snap like Jimmy did. When you watch and actually listen to his words inth tutor center, it was very clear there were multiple underlining issues. He already attempted suicide before this. He simply snapped. Unfortunately, it came sooner in a devastating situation rather than later because I truly believe he would have at some point - whether in a big or small way. And to blame Rachel for that isn't fair. She didn't put that gun in his hands so while I sympathize with Jimmy greatly, he chose that. Besides, Brooke didn't know it was Rachel who released the tape so again...how does that justify Brooke's actions?
Brooke wanted to pay back Rachel for outing her masturbating. Please. That's not so bad. Maybe a little embarrassing but it's also not the first time that particular issue has been brought up. In 104, they were playing "I never" and Teresa said "I've never had sex with anything made out of plastic" and Brooke shamelessly took a drink. Hello! And now she has an issue with it. Give me a break. Brooke maliciously broke into a locked cabinet in someone else's home and blew up incriminating photos of Rachel and posted them all over school. She made fun of someone's physical appearance in a truly disgusting way. That's a big difference from what Rachel did at the cabin. As Mouth asked "did she learn anything from the shooting?".
Now I'm not saying Rachel didn't do some cruel things herself (obviously, she did) but nothing she did to Brooke justifies what Brooke did to her.