|Stewie gave Brian his intelligence
Every fan of Family Guy knows that despite their differences and numerous feuds, Brian and Stewie are besties. I mean shit they literally made an episode called 'Brian and Stewie' where their deep bond and connection sways Brian away from committing suicide. But the other day I was watching Family Guy and something struck me. What if Brian was just an ordinary dog until Stewie gave him human intelligence? You may think 'that's crazy' but here's why:
BRIAN IS THE ONLY ONE WHO KNOWS OF STEWIE'S INVENTIONS
We see numerous times throughout the series Stewie showing his inventions to Brian, and he never shows them to anyone else. In season 15 Stewie and Brian take Chris on a trip to the past to help him prepare for a History test the next day, but Stewie exercises extreme caution to make Chris think it was a dream. In another episode, Brian shows his numerous girlfriends Stewies inventions, but when he finds out he is furious. Why? Because he wants no one to know that he is responsible for Brian's intelligence.
2. STEWIE'S REACTION TO BRIAN'S DEATH
In the season 14 episode, life of Brian, Stewie and Brian are playing hockey on the road (stupid right?). While this is happening Brian is ran over by a car, which rattles and depresses the Family, but we see Stewie is affected the most. Simply because one of his greatest achievements has just been destroyed. A dog that thinks like a human.
3. VINNY AND THE FAMILY
You may ask why Vinny (whom the family adopts after Brian's death) can talk. I have 2 possible theories. Either the government or some sort of illegal experimentation lab gave Vinny his intelligence, or Stewie's rival Bertram created Vinny. Once again Stewie encounters Bertram with Brian, and we see bertram is very jealous and hateful of Stewie, so he may have made a talking dog of his own. My final end to tie up is why the family isn't surprised about Brian being able to talk. Stewie has so many inventions, he no doubt erased the family's memories of a normal dog, which led them to think that Brian had always been this way. He may have also repeated this process with Peter and Lois`s friends, and if he had enough power, all of Quahog.
Finally I would like to address the theory that Family Guy is how Stewie views the world. I think that this is not likely the case seeing as there are many pop culture references and cameos in Family Guy that Stewie would not be aware of. It just does not make sense.So that's my theory. Hope you enjoyed