This is a bit of a dim question re au pair's airfare at end of time with us.

[MrsSchadenfreude]

We were originally going to be paying for her to go home to Middle of Nowhere, Eastern Europe, to her local airport at vast expense. She is now going from us straight to a job in Dublin. Question is, who pays her airfare? We can pop her on Ryanair for peanuts, and would be happy to do this, but shouldn't her new employer be paying her airfare really? She is going to be full time nanny.

If her new employer agreed (with her, as part of her package) to pay it then yes they should. But there's no reason why they "should" have agreed to do that iyswim. I think if you had agreed to pay her expensive airfare it would be reasonable to pay her cheap onward fare

I have no problem with paying, in principle, but think it would be nice if new employer offered.