Riley was introduced in the beginning of Season 4 as a TA for Professer Walsh, helping her in her classes. It is later on that we find out that Riley is a Commando for the Initiative. He captures and kills Demons for them with his squad of other collage students.

He quits the Initiative because they capture Oz and do tests on him, which he feels is wrong and so helps Oz to leave. Then, when the Initiative is attacked from within Riley, Buffy and the Gang manage to stop the Demon's and rescue most of the people.

In Season 5 Riley leaves Buffy because he feel's that she doesn't love him, and he believes that she doesn't want him to stay after catching him in the arms of a Vampire. The truth is that Buffy was too late and couldn't stop him leaving for a covert military operation.

In Season 6 Riley returns to Sunnydale and asks Buffy to help him follow a demon. Buffy gets a shock when she meets Riley's new wife, they all kill the Demon's eggs and Riley and his wife leaves.