Adjutant back on the eighteenth floor, apparently the subject of Samantha's seduction coaching for Bigs.
During the ride back to the Saferoom, Carl overhears Samantha giving Bigs advice on how to seduce someone. If he doesn't know better, he thinks, they sound like they are talking about Tart, the adjutant now back on the Eighteenth Floor.
It's a small, ridiculous domestic thread running underneath the retreat, the orbital shooting, and the standoff with Epitome Tagg.
Adjutant on the eighteenth floor and the apparent target of Bigs's romantic ambitions.