The Big Lebowski - Character Arc

First off I think "character arc" is a misleading term.

I like to think in terms of character growth and character change.

The "Dude" is a pacifist.

He takes up the opposite stance "To take a Stand"

Having been a part of the shit storm that "taking a stand" leads him on...

He returns to his pacifism


Is this character growth?  - I think so.  I think he learned that who he is, is who he should be.  It's a confirmation of his original beliefs.

I think we the audience/reader like it is, 1) it's funny to see a pacifist take a stand 2) we empathize with a character who agrees to put his belief system aside to try someone else's


Now at the start of the movie you've got The father Walter, The mother "Dude", and the child Donnie.

In another movie version you would have The father i.e. Walter replaced by Maude but because of her feminist stance she wants no part of the Dude in their unborn childs life.

The "unborn child and the Dude" replaces "Donnie and the dude's" relationship.

Is this character change? - No.  Not technically.  The dude does not form a new relationship with Maude.

That said I think we the audience/reader are okay with it is because we see that Maude will be fine on her own as a single mother.  And we probably wouldn't want the Dude being responsible for a child.

After seeing how the man rolls, well, it's probably best he just abides.  And takes it easy.