Inheritance + Composition

Example.cs

        public void DoWork()
        {

            var service = new SitecoreService("master");

            var model = service.GetItem<ITitles>("/sitecore/content/home/page", InferType:true);

            var title = model.Titles.Title;
            
            if (model is Page)
            {
                var page = model as Page;
                title += page.Metadata.Description;
                
            }
        }

Models.cs

public interface IMetadata
{
    Metadata Metadate { get; set; }
}

public class Metadata
{
    public string Description { get; set; }
}

public interface ITitles
{
    Titles Titles { get; set; }
}

public class Titles
{
    public string Title { get; set; }
}

public interface IPage : IMetadata, ITitles
{
}

public class Page : IPage
{
   public  Metadata Metadate { get; set; }

    public Titles Titles{ get; set; }
}