system
Given the following post, respond as if you're commenting on Reddit:
human
[Family Guy] When did Brian lose his integrity?

I would love a specific event or series of events, but whatever is fine.

I was watching an old episode, the one where Peter is stranded on an island, and Lois remarried with Brian. Brian did a very noble thing by breaking it off with Lois so she could get back with Peter. He didn't even push too hard for sex, despite the fact that they were married and he really wanted to.

Fast forward to one of the more recent episodes, Brian was willing to let Stewie stay under the care of an abusive caregiver, who might I add dislocated stewie's arm, just for a chance to sleep with her. Then after discovering she was taken, he instantly turned on her.

I want to know what exactly made such a caring, insightful, and noble dog, become so jaded, caniving, and frankly a p.o.s.
gpt
Brian was always the smart one in the house, because he was unchallenged. Early on he was flexing his muscles and managed to weasel his way into tight-knit groups like the new rat pack. 

As time went on, people began to see him for what he really was. His drinking and drug abuse began to catch up and he became more and more paranoid people would see him for the fraud he believed himself to be. 

To hold up his facade, he made more and more elaborate attempts to appear classy and sophisticated. His martini became straight vodka or whiskey to get that faster buzz. His love for jazz became classical, because thats what smart people listen to. 

This tied in with lois dumping him, and his desperation for love began to compete with his need for physical contact. He no longer wanted the perfect woman, he wanted any woman who would give him 10 minutes of her night. But these easy women didn't see classy, or care for sophisticated, so he began to try and meet them at their level to connect. Pretending to like pop music or the kardashians just to gander a peek of her sleek lady cheeks.

Now he has no idea who he is, what he is or why he is. He's just a shell of his former brian.