What is the fate of a black hole embedded in an expanding universe?
  Within a large class of exact solutions of the Einstein equations describing a black hole embedded in a Friedmann universe it is shown that, under certain assumptions, only those with comoving Hawking-Hayward quasi-local mass are generic, in the sense that they are late-time attractors. 
Valerio Faraoni, Changjun Gao, Xuelei Chen, and You-Gen Shen