diff --git a/DTOs/LibraryApiV10.custom.cs b/DTOs/LibraryApiV10.custom.cs
index de302e64..95454cdb 100644
--- a/DTOs/LibraryApiV10.custom.cs
+++ b/DTOs/LibraryApiV10.custom.cs
@@ -9,6 +9,9 @@ namespace DTOs
 	{
 		public IEnumerable<Person> AuthorsDistinct => Items.GetAuthorsDistinct();
 		public IEnumerable<Person> NarratorsDistinct => Items.GetNarratorsDistinct();
+		public IEnumerable<Series> SeriesDistinct => Items.GetSeriesDistinct();
+		public IEnumerable<Ladder> ParentCategoriesDistinct => Items.GetParentCategoriesDistinct();
+		public IEnumerable<Ladder> ChildCategoriesDistinct => Items.GetChildCategoriesDistinct();
 
 		public override string ToString() => $"{Items.Length} {nameof(Items)}, {ResponseGroups.Length} {nameof(ResponseGroups)}";
 	}
@@ -41,8 +44,12 @@ namespace DTOs
 		public DateTime? DatePublished => IssueDate?.UtcDateTime; // item.IssueDate == item.ReleaseDate
 		public string Publisher => PublisherName;
 
-		// future: need support for multiple categories
+		// these category properties assume:
+		// - we're only exposing 1 category, irrespective of how many the Item actually has
+		// - each ladder will have either 1 or 2 levels: parent and optional child
 		public Ladder[] Categories => CategoryLadders?.FirstOrDefault()?.Ladder ?? new Ladder[0];
+		public Ladder ParentCategory => Categories[0];
+		public Ladder ChildCategory => Categories.Length > 1 ? Categories[1] : null;
 
 		// LibraryDTO.DownloadBookLink will be handled differently. see api.DownloadAaxWorkaroundAsync(asin)
 
diff --git a/DTOs/LibraryApiV10Extensions.cs b/DTOs/LibraryApiV10Extensions.cs
index 2f000b88..03f04c86 100644
--- a/DTOs/LibraryApiV10Extensions.cs
+++ b/DTOs/LibraryApiV10Extensions.cs
@@ -11,6 +11,18 @@ namespace DTOs
 			=> items.SelectMany(i => i.Authors).DistinctBy(a => new { a.Name, a.Asin });
 
 		public static IEnumerable<Person> GetNarratorsDistinct(this IEnumerable<Item> items)
-			=> items.SelectMany(i => i.Narrators).DistinctBy(a => new { a.Name, a.Asin });
+			=> items.SelectMany(i => i.Narrators).DistinctBy(n => new { n.Name, n.Asin });
+
+		public static IEnumerable<Series> GetSeriesDistinct(this IEnumerable<Item> items)
+			=> items.SelectMany(i => i.Series).DistinctBy(s => new { s.SeriesName, s.SeriesId });
+
+		public static IEnumerable<Ladder> GetParentCategoriesDistinct(this IEnumerable<Item> items)
+			=> items.Select(l => l.ParentCategory).DistinctBy(l => new { l.CategoryName, l.CategoryId });
+
+		public static IEnumerable<Ladder> GetChildCategoriesDistinct(this IEnumerable<Item> items)
+			=> items
+				.Select(l => l.ChildCategory)
+				.Where(l => l != null)
+				.DistinctBy(l => new { l.CategoryName, l.CategoryId });
 	}
 }
diff --git a/__TODO.txt b/__TODO.txt
index cfcd323d..1ca2ab30 100644
--- a/__TODO.txt
+++ b/__TODO.txt
@@ -68,6 +68,7 @@ TONS of expensive conversion: GetLibraryAsync > string > JObject > string > Libr
 
 -- begin ENHANCEMENT, CATEGORIES ---------------------------------------------------------------------------------------------------------------------
 add support for multiple categories
+when i do this, learn about the different CategoryLadder.Root enums. probably only need Root.Genres
 -- end ENHANCEMENT, CATEGORIES ---------------------------------------------------------------------------------------------------------------------
 
 -- begin LEGACY ---------------------------------------------------------------------------------------------------------------------