A content processing service may analyze an item of original content and identify several objects, attributes of those objects, and relationships between those objects present in the item of original content. The content processing service may also analyze a source graph, such as a social graph or supplemental graph, and identify several objects, attributes of those objects, and relationships between those objects present in the source graph. The content processing service may customize the item of original content by selecting an original object and selecting a source graph object. One or more of the attributes or relationships of the selected original object in the item of original content may be replaced by one or more of the attributes or relationships of the selected source graph object, thereby forming an item of modified content.