An expandable play set as well as associated methods, communication protocols, and tangible computer-readable media are disclosed. The play set may generate interactive responses based upon which characters are coupled to a base unit and to which connectors of the base unit the characters are coupled. A character may include circuitry that permits the character to identify to which connector of the base unit the character is coupled. Such circuitry may also permit the character to identify and communicate with other characters that are also coupled to the base unit. Based upon obtained identifiers, the character may generate or otherwise cause suitable interactive responses such as activating a load in the base unit, turning on a light in the base unit and/or character, and/or generating a suitable audible response via an audio speaker of the character.