Season 7|Episode 3 Road to Germany.
Season 9|Episode 16 Big Bang Theory.
Season 10|Episode 5 Back to the Pilot.
Brian died November 24th 2013, in the 6th episode of Season 12 | Life of Brian.---In the 8th episode Christmas Guy that aired on December 15th 2013, Stewie altered the time line and Brian was never hit & killed by the car, thus returning to the show.
According to an interview with creator Seth MacFarlane, Stewie's sexuality is left ambiguous. As for Brian, he has had several female companions over the years, so I highly doubt that he is gay.
Your question is vague to say the least but you might be describing Season 5|Episode 7 Chick Cancer when Brian tells Stewie "it's not your fault"
The main characters in Family Guy are Peter, his wife Lois, children Chris, Meg, and Stewie, and dog Brian. Peter, Stewie, Brian, and Quagmire are all voiced by creator Seth MacFarlane.
Stuck Together, Torn Apart
All of the "Road to" episodes are primarily Stewie and Brian centered episodes, also of the episode titled Brian and Stewie
This happens in many episodes. It is just Stewie trying to annoy Brian. Throughout Season 7 it happens more.
Rather vague question but if your asking if any characters haven't been in episodes. Yes, there has been episodes that did not feature every member of the Griffins.Brian and Stewie for instance, obviously featured only Brian & Stewie.
No, Joey Slotnik has never voiced main characters on Family Guy, he has appeared in 8 episodes though.
Brian & Stewie's Emmy appearance & performance wasn't part of any Family Guy episode.
Family Guy
Yes.
Saving Private Brian
Saving Private Brian.
The evil Stewie clone does it in The Hand That Rocks the Cradle
Brian tell Stewie the truth when they are stuck in the bank vault in the episode Brian & Stewie
No.