Bioengineering
It is implied throughout the series that they have interfered with the evolution of many species, including humans, Minbari, Narns, and Drazi. Each of these species "see" Vorlons outside their encounter suits as some type of religious or mythological character particular to their culture. The Centauri or at least Londo Mollari, apparently see nothing when looking at Vorlons. It could imply that they have not been influenced or altered by the Vorlons or could indicate Londo's status as an ally of the Shadows. During the episode "Secrets of the Soul", a flashback is shown of Lyta Alexander floating in a Vorlon test tube; the camera then pans past two other test tubes showing a Drazi fetus and then a Centauri fetus. This implies that the Centauri have been altered by the Vorlons.
The Vorlons also have the ability to alter alien species to better serve their purposes. Lyta Alexander was given "gills" on her neck that allowed her to breathe the atmosphere within the Vorlon ambassador's chamber, though the Narn can do much the same. Vorlons also use other beings as receptacles for a fragment of their personality, allowing them to travel widely without being noticed.
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