Riku is Sora's friend and former antagonist in KH. He ended up getting possessed by Xehanort after succumbing to darkness, but managed to break free from his spell and was able to take on the powers of darkness for good purposes. Chernabog and his son plan to drag Riku back into Darkness in order to provide Mirage with her own son to watch over.
But now, Riku has been recruited forcefully into the Fang Empire before that can happen so that Makuta can have his own keyblade warrior in the empire. However, the keybearer won't be taken control of that easily, and is now being used by the Dark Dragon and Chopsuey to overthrow Emperor Fang in a little scheme of theirs.
Roleplays of the series have revealed that he's fully on the side of good, and is spying on Emperor Fang so that the Shell Louge Squad can find a way to defeat the evil snake. Also Cynder has become a sister like figure to Riku as well as his bonded Dragon since Spyro became Kairi's bonded Dragon since Riku and Cynder have two things in common: Their exposers to the Darkness and their Avatar forms under the teachings of Saldaron the Nega Chesire Cat. In the Seas of Captain Legend Episodes of the Second Season of the SpongeBob and Friends Chronicles Adventures series, Riku gets an Oc Girlfriend named Vanessa and the two start a Diego and Shira style forbidden Romeo and Juliet romance untill Captain Blot's Defeat at the hands of Spyro.