The driveway looped around in front of an old two-story house, torn down in sections over the years and rebuilt out of cinder block because of termites. Father rarely ventured upstairs anymore, but wings had been added to the house at ground level. Willem parked his truck at the base of a flagpole flying the Dutch tricolor beneath a larger Stars and Stripes. Before shutting off the engine he sat there for a minute, letting the A/C run, and using PanScan—one of several competing apps in the anonymized contact tracing space—to check his immunological status versus that of everyone currently in the house. Since Willem was the interloper, he was the most likely to be bringing new viral strains in to this household.