[Class]
    [Serializable]
    public class Model
    {
        [Id(0, Column="Id", Type="int",Name = "Id")]
        [Generator(1, Class = "identity")]
        public virtual int Id { get; protected set; }

        [Property]
        public virtual string ModelName { get; set; }

        [Property]
        public virtual bool IsReference { get; set; }

        [ManyToOne(Class = "Database.Entity.Model", Column = "ReferenceModelId")]
        public virtual Model ReferenceModel { get; set; }

        [OneToMany(Class = "Database.Entity.RuleModelState", ClassType = typeof(Database.Entity.RuleModelState))]
        public virtual List<RuleModelState> RuleStates { get; set; }

        

        

        #region Конструкторы

        public Model()
        {
            RuleStates = new List<RuleModelState>();  // По совету джависта 
        }

        #endregion

    [Class]
    [Serializable]
    public class RuleModelState
    {
        [Id(0, Column = "Id", Type = "int", Name = "Id")]
        [Generator(1, Class="identity")]
        public virtual int Id { get; set; }

        [ManyToOne(Class = "Database.Entity.Model", Column = "ModelId")]
        public virtual Model Model { get; set; }

        [ManyToOne(Class = "Database.Entity.CustomizationRule", Column = "RuleId")]
        public virtual CustomizationRule CustomizationRule { get; set; }

        [Property(Type = "int", Column = "EnabledState", Name = "EnabledState")]
        public virtual EnabledState EnabledState { get; set; }

        [Property(Type = "int", Column = "Recommendation", Name = "Recommendation")]
        public virtual EnabledState Recommendation { get; set; }

        [Property]
        public virtual bool? IsValid { get; set; }

        #region Конструкторы

        public RuleModelState()
        { }

        #endregion

Model result;
//result = session.Get<Model>(modelId);
result = (Model) session.CreateCriteria<Model>().Add(Restrictions.Eq("id", modelId)).SetFetchMode("RuleStates",FetchMode.Join).UniqueResult();