Using the analyze action you can gain information about what the target wants and their character aspects if there are any. Each turn the list of actions is regenerated from a list of possible ones.

The purpose of any conversation is to gain the consent of the interlocutor. At this point a new menu action 'Converse With' opens up which leads into the conversation mode. How it works is you first need to complete the tutorial (open access to the timeline), then use one host for a period of time until the affinity between you grows to a high degree. The parasite can chat with its host and later with the other NPCs.