I first chose to save my friends, because that was basically the entire point of the game. But I reloaded my save before the credits ended, and then chose to kill my friends and join Citra which made absolutely no sense because there's no way that Jason would have killed his brother and friends. It was a completely ridiculous ending, and it shouldn't have even been a choice. The game should have just had the one ending with Jason saving his brother and friends, and leaving with them. But I also can't deny that having first person sex with Citra was nice...UNTIL SHE STABBED ME!!!!
It made complete sense. Not only was he completely changed by the experience, he was on hardcore drugs. A sense of belonging has a huge impact on people. In real life people join gangs and rape and murder strangers and sometimes family members, just to have that sense of belonging. If you think it made no sense, you must be a privileged kid with no sense of the real world....like Jason started out as.
It made complete sense. Not only was he completely changed by the experience, he was on hardcore drugs.
He just risked his life to rescue his brother right before going to the temple, so he wasn't completely changed otherwise he wouldn't have rescued him. And the drugs that Citra gave him had worn off by the time that he got to Liza.