WOULD RATHER / WOULD SOONER + clause with the past perfect subjunctive

Would rather/sooner + clause with the past perfect subjunctive expresses preferences or wishes about the past. The subject of would rather/sooner and the subject of the subjunctive are different:

I'd rather this whole thing had never happened. (I wish it had never happened.)
What would you rather I had done? (What would you have preferred me to do?)

This pattern can be rephrased by using a third conditional with prefer:

I'd prefer it if this whole thing had never happened.