Craft an image using the watercolor style, depicting a grand meeting of the 12 key figures in Greek mythology. Each should be attractively portrayed, radiating their unique attributes and powers. Next, create an accompanying scenario showcasing 12 Roman deities partaking in a similar gathering, their personas exuding their distinct memorability. The individuals should be portrayed in a manner reminiscent of the ancient stories and scriptures, bathed in a remarkable play of watercolor shades.