PeopleController.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;
using System.Xml.Serialization;

namespace MvcApplication56.Controllers {

    public class Person {

        public string Name { get; set; }
        public virtual ICollection<Order> Orders { get; set; }
    }

    public class Order {

        public string Name { get; set; }
    }

    public class PeopleController : ApiController {
        
        public IEnumerable<Person> Get() {

            return new List<Person> { 
                new Person { 
                    Name = "Foo", 
                    Orders = new List<Order> { 
                        new Order { Name = "Bar" }
                    } 
                },
                new Person { 
                    Name = "Foo", 
                    Orders = new List<Order> { 
                        new Order { Name = "Bar" }
                    } 
                }
            };
        }

        public Person Get(int id) {

            return new Person {
                Name = "Foo",
                Orders = new List<Order> { 
                    new Order { Name = "Bar" }
                }
            };
        }
    }
}