Rivas is part of the Followers of the Apocalypse and has been working with the NCR on getting HELIOS One working for years but hasn't made any progress, especially since the idiot showed up to also try and "help" in fixing HELIOS One.
ED-E My Love: Talking about technology with Rivas when ED-E is in your party will trigger an audio log.
That Lucky Old Sun: Rivas will give you Eastern reflector control terminal password needed to access the reflector mainframe. He also tells the player that he suspects Helios One may be more than a simple energy plant, as Poseidon Energy was also concerned with weapons. He also remarks that it is convenient that the NCR hired an idiot who will not figure out the true purpose of the plant. He only reveals this information if he feels the player will not use this information to arm the secret weapons, Archimedes I and Archimedes II.
When speaking to Ignacio with Intelligence 3 or lower, you have unique topics such as: "Me help shoulders make shinies warm," "Who are Flowers of Pock-lips?" and "Do Flowers and NCR Bear play together?" It's also possible to respond with "pizza" and "warm" instead of "peace" and "war" when he asks you which you support.