Emily too was a writer like Mable but in Fiction

...but of fiction. Some would include some commas, but I think they would clutter; you probably should, however, use a comma after Mable.

Thanks.

When I say this to myself, it doesn't sound very natural. When do you think this sentence would be used in everyday conversation?

Emily, like Mable, was a writer, but in fiction.

It's perfectly natural and could be used whenever you have that meaning to convey. The commas you included now are those that I would avoid, myself, to avoid clutter. They are not, however, incorrect. I still think you need the preposition of rather than in with fiction.

Thanks.

My book says 'in fiction' not 'of fiction'.

What's the difference?

My two cents:

* A successful writer of romantic fiction.

Tom

AnonymousMy book says 'in fiction' not 'of fiction'.What's the difference?

The writer of your book writes less natural English than Philip or Tom.

By the way, The name is normally spelt Mabel.