It all started with a harmless conversation. Williams was evaluating its driver options for 2018 and Robert Kubica wanted to find out whether he still had the ability to drive a Formula 1 car at a high level, after sustaining life-threatening injuries in a rally crash back in '11.
Renault started the evaluation, then Williams chose to pick up the baton. It and Kubica met to discuss how they could help each other out. There were echoes of 2013, when Felipe Massa and Williams started conversations because their aims aligned.
The difference in this instance was that Williams first needed to evaluate Kubica's physical ability to drive an F1 car, given the severe injury he suffered to his right arm, and then find out if he was the quickest driver available to the team.