Babylon 5 is under quarantine throughout the episode, with the Markabs enacting a self quarantine. Delenn and Lennier decide to offer comfort to the quarantined Markab, without knowing if they will fall ill as well. Captain Sheridan tries to convince Delenn not to shut herself in with the Markab as he will not be able to let her out again.
Delenn and Lennier invite Sheridan to dinner in return for the human-style dinner Sheridan shared with Delenn earlier in the season.
Sheridan tells Delenn to call him "John" in a scene that shows the beginning of romantic feelings in their relationship. Later Delenn cries on John's shoulder, grieving for the dead Markab.
Lt. Keffer's "expeditions into hyperspace" are mentioned and curtailed.
An entire alien species in the Babylon 5 universe becomes extinct. Later in the series Sheridan destroys their jumpgate in order to escape from a Shadow vessel, and to prevent grave robbers from pillaging the dead planet.