Andrew (full name: Andrew Wonderful, according to his driver's license) is a random guy who Matt said would get focused on more in Season 7. To our knowledge, before episode 76 he knew neither Joel nor Phil, and Joel claims not to have known about him either. Elly describes Andrew in one word as being "assertive".
Andrew often spews incoherent babble rather than saying anything that's really important. Despite this, he is often depicted as being more sensible compared to Elly. According to Elly and Brad, Andrew drools a lot, but he claims that this is untrue.
He was the only character who volunteered to go into space with Elly at the end of season 5, though his reasons for doing so are unknown. It's possible that he has his own secret agenda. Or perhaps he's just a nutcase.
In Fickle Nickel, it was hinted that Andrew had been actively stalking Elly. His comment that he and Elly should make love to stay warm in Elly in Chains further suggested that he may have some weird thing for her. After their kiss in The Day The World Did Stuff, Elly and Andrew were officially in a relationship together, much to the frustration of Phil. In Bonus Stages, Elly broke up with Andrew, citing advice from her inner child.
How he got off Hydrox is unclear, but he is seen (with a since-vanished red mark on his forehead and wearing a strange expression) behind Rya in the last shot of The Day The World Did Stuff.
Andrew recently tinkered with Rya, turning her into a fully human woman (thus leading to her permanent death), and leading many to believe he is some sort of hacker. He is also believed by some in the fanbase to be Evil, although this is disproved in Joel Fights Crime, Phil Rewrites Time.
Andrew is NOT, as a lot of people thought he was, Andrew Kauervane, who created "My God, ROBOTS!" - a macabre style Flash cartoon on which Matt does the musical score.