I have a question about grammer 'I'd rather you didn't'.
I have a question about grammer ' I'd rather you didn't '

I learned some phrase.

For example,
I'd rather say
I'd rather not say.
It was a rather difficult question.

In this way, I think 'rather' was followed by verb and adjective.
But in this case, that isn't so.
Is it irregular phrase ? or Is it natural that 'rather' was followed by subject ?

Question

I have a question about grammer 'I'd rather you didn't'.
I have a question about grammer ' I'd rather you didn't '

I learned some phrase.

For example, 
I'd rather say
I'd rather not say.
It was a rather difficult question.

In this way, I think 'rather' was followed by verb and adjective.
But in this case,  that isn't so.
Is it irregular phrase ? or Is it natural that 'rather' was followed by subject ?

Answer

I'd rather somebody did (or had done) ..... is a typical use.

Answer

You can understand the grammar as "I'd rather (that) you didn't."  So "I'd rather" is followed by a clause with the verb in past form (it's actually subjunctive form, eg. a wish).

"Rather" is rather flexible! :)