We are introduced to the concept of flashes in the pilot episode of Roswell when Max of necessity establishes a connection with Liz to heal her. The connectivity this action requires causes him to experience flashes of Liz’s life –chief of these a homemade dress of cupcake pattern that mortified her. This kind of flash works reciprocally; just as Max experiences flashes of Liz’s life, so she sees those same memories as filtered by Max’s perception of them, and of herself.
As Max and Liz’s relationship develops, so too do the flashes, which are largely tied to their intimacy, although we later learn that on occasion these can be induced by contact with an object tied to an especially evocative incident. Thus in season 1 episode Missing Max experiences a flash on coming into contact with a CD in Liz’s room and deduces Kyle has been there recently. Missing is also the first time we put a name to the flashes; Max describes them as flashes of intense or heightened sense awareness.
Different to Dreamwalking or other alien powers we encounter of the course of the series, the flashes are common to all of the aliens, though not all of them tap so readily into the vulnerability that seems to be necessary to facilitate them. Thus we discover that while Michael vividly experiences a flash from Maria –of a red-sneakered girl with her dog –Maria does not experience a reciprocal flash from Michael, something which briefly becomes a source of tension between them. It is not until Departure at the end of season 2 that Michael can finally open up enough to send Maria a flash of his own.
As we move into the third season of Roswell our sense of the flashes evolves still further when Liz begins to experience not only memories but also vision-like projections of the future. These anticipatory flashes seem, unlike the usual flashes, to be singular to her, and are still developing when the gang finally departs Roswell.