I asked this question on the English Language & Usage site but I thought it useful to ask here, too, since it is a writing issue.
I'm writing a book that's primarily set in America; my protagonist is half-American, half-British but speaks with a strong British accent and uses British dialects (e.g. she refers to sidewalks as pavements). Specifically, I'm stuck trying to figure out how I should be spelling -ise/-ize words.
I'm confident that I've got the differences in dialogue down, but as this story is also written in the third person/present tense, how should I be writing the narration? In British or American English?
The POV also often switches between my British character and her American partner, so should my narration style change to fit whoever is the primary character in that chapter?