Evan Landon is the infant son of Andrew and Michele Landon. What we know of him comes from "Gifted", "Of Human Bonding", and The Daria Database.
Michele left her position as "Senior VP at US World" to be with Evan and there is tension between her and Andrew over when she can return to the business world; she wants to put him in daycare at some point, which Andrew refuses to allow. She lets slip that Evan was an unplanned pregnancy.
Andrew dotes on the baby and has grand visions of football and other father/son bonding after raising two daughters. Andrew even refers to Evan as a "linebacker" as if he's already playing.
His sister Rachel Landon hates Evan for usurping her as the "baby" of the family.
Evan rarely appears due to being an off-screen infant. A notable exception was JoeMerl's "Sitting on the Sidelines", where Evan has become a major football fanatic but is never able to play it.