Binary configurations after applying a natal kick during the formation of the first BH. Masses and separations shown correspond to pre-collapse orbital parameters. Each point represents a single detailed binary evolution of the BH and its companion star. Colours show different binary outcomes: in green, we represent merging binaries during a CE phase, in red we show binaries which unexpectedly end due to numerical problems, while blue points are binaries reaching the second core-collapse stage. The arrow represents the location on this plane of the binary that receives no natal kick.