The episode where Brain and Stewie are locked inside a bank volta, vault over night. Easily could be my favourite one on the whole history of the mostra because of how much it contrasted to all the others. Some of the più serious dialouge near the end really got me. It was so sweet and gave me a totally different look towards the odd duo. ♥
Also, there was a moment in "New Kidney In Town", where Brian offered his organ for Peters' transplant, that almost made me well up. I never thought Family Guy could ever do that to me.
There have been other touching scenes, but they're usually very brief in comparision to these.
When Peter is asked to stop drinking Red toro and tries to make his own home made red toro using Kerosine. So he drinks it and his kidneys fail. So Brian decides to give his kidneys to Peter. The part where there at the hospital and Brian and Peter have a touching moment. And Peter cries cause he can't believe Brian is giving his life to save Peter's. That got me going!
An episode called "Brian and Stewie". There were no cutaways and the only characters in the episode were them. The message at the end really got to me. If te haven't seen it, watch it. This is the only episode I've cried over besides Brian's death.
