Stewart Gilligan Griffin (a.k.a. Stewie) is a fictional one year old character in the animated series called Family Guy. He is very sophisticated and has an advanced vocabulary.
He is completely obsessed with world domination and also trying throughout the episodes to kill his mother, Lois because of the nine months he had to spend in her which he calls the "ovarian Bastille." Stewie has a brother named Chris and a sister named Meg, but also a half-brother which the Griffin family is unaware of named Bertram.
The voice of Stewie is done by Seth McFarlane in an English accent. It never seems awkward at all to the people in the show when Stewie seems to have firearms and and other such weapons. He even constructed secret passages in his bedroom that house all of his weapons as well as he built fighter-jets, robots, mind control devices, a time machine and such.
What is funny to me is that it is hard to tell if the family actually hears Stewie talking because at some points they respond back to him and then at some times, when he talks about world domination or killing Lois, no one says anything back to him.
For example in an episode called "Mind Over Murder" Stewie says "victory is mine!" and then his mother Lois responds back with "Yes, and this cake is yours too." So obviously their are three ways you can look at it, either they ignore him, don't hear him, or don't take him seriously. In an episode called "Mr.
Griffin Goes to Washington" Lois says, "My god, it all makes sense now. My baby is some kind of diabolical genius bent on world domination!" Stewie then replies back (clapping) Bravo, Lois. The last horse finally crosses the finish line. Which Louis then replies back with, "Stewie! All these months I should have paid attention to what you've said.
You're an evil child. Why, why did I have to go and smoke pot when I was pregnant with you?" Being that Stewie is supposed to only be one years old and does not seem to age throughout the seasons he talks about things from way before his time as if he were there. He is such a sophisticated child, while on the other hand he loves child things. Rupert, which is his teddy bear is like a best friend to Stewie; Stewie talks to him as if he were a real person.