Steve is a one-off character in H2O: Just Add Water played by Damien Garvey.
Steve is in the business of making counterfeits. Chris works with him, and seems to be the errand boy. Steve sent him to buy some food for the road, and was disappointed when it was all the same.
After Chris had invited Rikki Chadwick on board to reimburse her with real money, Steve noticed Rikki starting to act weird, and subdued her, tying her up and taping her mouth shut.
Eventually Rikki's friends showed up and called the police, Will even tossed their counterfeits into the river. Chris and Steve tried to run away, but were arrested.