In my headcanon Duke is a personified Ouija board planche. Just like the planche is the go-between for the user and the Ouija board, Duke is the go-between for

In my headcanon Duke is a personified Ouija board planche. Just like the planche is the go-between for the user and the Ouija board, Duke is the go-between for the user and the tablet computer for which Java was originally designed. It might be a bit of a stretch, but he was originally more than a mascot but a "software agent" through which the user's actions were carried out, a sort of more active version of Clippy.