diff --git a/lib/document.js b/lib/document.js
index 14a33ef323..ed9e347adc 100644
--- a/lib/document.js
+++ b/lib/document.js
@@ -806,8 +806,8 @@ function init(self, obj, doc, opts, prefix) {
               reason: e
             }));
           }
-        } else if (opts.hydratedPopulatedDocs) {
-          doc[i] = schemaType.cast(value, self, true);
+        } else if (schemaType && opts.hydratedPopulatedDocs) {
+          doc[i] = schemaType.cast(value, self, true, undefined, { hydratedPopulatedDocs: true });
 
           if (doc[i] && doc[i].$__ && doc[i].$__.wasPopulated) {
             self.$populated(path, doc[i].$__.wasPopulated.value, doc[i].$__.wasPopulated.options);
diff --git a/lib/model.js b/lib/model.js
index 7edbce6ce2..bd8e60ec97 100644
--- a/lib/model.js
+++ b/lib/model.js
@@ -1461,7 +1461,7 @@ function getIndexesToDrop(schema, schemaIndexes, dbIndexes) {
  * @param {Object} [options]
  * @param {Array<String>} [options.toDrop] if specified, contains a list of index names to drop
  * @param {Boolean} [options.hideIndexes=false] set to `true` to hide indexes instead of dropping. Requires MongoDB server 4.4 or higher
- * @return {Promise<String>} list of dropped or hidden index names
+ * @return {Promise<Array<String>>} list of dropped or hidden index names
  * @api public
  */
 
@@ -3688,7 +3688,7 @@ Model.castObject = function castObject(obj, options) {
     }
 
     if (schemaType.$isMongooseDocumentArray) {
-      const castNonArraysOption = schemaType.options?.castNonArrays ??schemaType.constructor.options.castNonArrays;
+      const castNonArraysOption = schemaType.options?.castNonArrays ?? schemaType.constructor.options.castNonArrays;
       if (!Array.isArray(val)) {
         if (!castNonArraysOption) {
           if (!options.ignoreCastErrors) {
diff --git a/lib/schema.js b/lib/schema.js
index ddde465929..60124f68e3 100644
--- a/lib/schema.js
+++ b/lib/schema.js
@@ -1939,13 +1939,11 @@ Schema.prototype.pre = function(name) {
  *     const Model = mongoose.model('Model', schema);
  *
  *     const m = new Model(..);
- *     m.save(function(err) {
- *       console.log('this fires after the `post` hook');
- *     });
+ *     await m.save();
+ *     console.log('this fires after the `post` hook');
  *
- *     m.find(function(err, docs) {
- *       console.log('this fires after the post find hook');
- *     });
+ *     await m.find();
+ *     console.log('this fires after the post find hook');
  *
  * @param {String|RegExp|String[]} methodName The method name or regular expression to match method name
  * @param {Object} [options]
@@ -2382,9 +2380,15 @@ Schema.prototype.virtual = function(name, options) {
             const PopulateModel = this.db.model(modelNames[0]);
             for (let i = 0; i < populatedVal.length; ++i) {
               if (!populatedVal[i].$__) {
-                populatedVal[i] = PopulateModel.hydrate(populatedVal[i]);
+                populatedVal[i] = PopulateModel.hydrate(populatedVal[i], null, { hydratedPopulatedDocs: true });
               }
             }
+            const foreignField = options.foreignField;
+            this.$populated(
+              name,
+              populatedVal.map(doc => doc == null ? doc : doc.get(typeof foreignField === 'function' ? foreignField.call(doc, doc) : foreignField)),
+              { populateModelSymbol: PopulateModel }
+            );
           }
         }
 
diff --git a/lib/schema/array.js b/lib/schema/array.js
index e424731e4d..a555c308cc 100644
--- a/lib/schema/array.js
+++ b/lib/schema/array.js
@@ -403,6 +403,9 @@ SchemaArray.prototype.cast = function(value, doc, init, prev, options) {
               opts.arrayPathIndex = i;
             }
           }
+          if (options.hydratedPopulatedDocs) {
+            opts.hydratedPopulatedDocs = options.hydratedPopulatedDocs;
+          }
           rawValue[i] = caster.applySetters(rawValue[i], doc, init, void 0, opts);
         }
       } catch (e) {
diff --git a/lib/schema/buffer.js b/lib/schema/buffer.js
index e5cec2e015..4d5c1af7d5 100644
--- a/lib/schema/buffer.js
+++ b/lib/schema/buffer.js
@@ -140,7 +140,7 @@ SchemaBuffer.prototype.checkRequired = function(value, doc) {
  * @api private
  */
 
-SchemaBuffer.prototype.cast = function(value, doc, init) {
+SchemaBuffer.prototype.cast = function(value, doc, init, prev, options) {
   let ret;
   if (SchemaType._isRef(this, value, doc, init)) {
     if (value && value.isMongooseBuffer) {
@@ -167,7 +167,7 @@ SchemaBuffer.prototype.cast = function(value, doc, init) {
     }
 
     if (value == null || utils.isNonBuiltinObject(value)) {
-      return this._castRef(value, doc, init);
+      return this._castRef(value, doc, init, options);
     }
   }
 
diff --git a/lib/schema/decimal128.js b/lib/schema/decimal128.js
index 70fcfecc60..136529ec04 100644
--- a/lib/schema/decimal128.js
+++ b/lib/schema/decimal128.js
@@ -180,13 +180,13 @@ SchemaDecimal128.prototype.checkRequired = function checkRequired(value, doc) {
  * @api private
  */
 
-SchemaDecimal128.prototype.cast = function(value, doc, init) {
+SchemaDecimal128.prototype.cast = function(value, doc, init, prev, options) {
   if (SchemaType._isRef(this, value, doc, init)) {
     if (isBsonType(value, 'Decimal128')) {
       return value;
     }
 
-    return this._castRef(value, doc, init);
+    return this._castRef(value, doc, init, options);
   }
 
   let castDecimal128;
diff --git a/lib/schema/number.js b/lib/schema/number.js
index d89ab7d63c..a5188a81cc 100644
--- a/lib/schema/number.js
+++ b/lib/schema/number.js
@@ -354,10 +354,10 @@ SchemaNumber.prototype.enum = function(values, message) {
  * @api private
  */
 
-SchemaNumber.prototype.cast = function(value, doc, init) {
+SchemaNumber.prototype.cast = function(value, doc, init, prev, options) {
   if (typeof value !== 'number' && SchemaType._isRef(this, value, doc, init)) {
     if (value == null || utils.isNonBuiltinObject(value)) {
-      return this._castRef(value, doc, init);
+      return this._castRef(value, doc, init, options);
     }
   }
 
diff --git a/lib/schema/objectId.js b/lib/schema/objectId.js
index cad05198ea..927a168df4 100644
--- a/lib/schema/objectId.js
+++ b/lib/schema/objectId.js
@@ -223,7 +223,7 @@ SchemaObjectId.prototype.checkRequired = function checkRequired(value, doc) {
  * @api private
  */
 
-SchemaObjectId.prototype.cast = function(value, doc, init) {
+SchemaObjectId.prototype.cast = function(value, doc, init, prev, options) {
   if (!(isBsonType(value, 'ObjectId')) && SchemaType._isRef(this, value, doc, init)) {
     // wait! we may need to cast this to a document
     if ((getConstructorName(value) || '').toLowerCase() === 'objectid') {
@@ -231,7 +231,7 @@ SchemaObjectId.prototype.cast = function(value, doc, init) {
     }
 
     if (value == null || utils.isNonBuiltinObject(value)) {
-      return this._castRef(value, doc, init);
+      return this._castRef(value, doc, init, options);
     }
   }
 
diff --git a/lib/schema/string.js b/lib/schema/string.js
index d62e233765..b832dbd988 100644
--- a/lib/schema/string.js
+++ b/lib/schema/string.js
@@ -586,9 +586,9 @@ SchemaString.prototype.checkRequired = function checkRequired(value, doc) {
  * @api private
  */
 
-SchemaString.prototype.cast = function(value, doc, init) {
+SchemaString.prototype.cast = function(value, doc, init, prev, options) {
   if (typeof value !== 'string' && SchemaType._isRef(this, value, doc, init)) {
-    return this._castRef(value, doc, init);
+    return this._castRef(value, doc, init, options);
   }
 
   let castString;
diff --git a/lib/schema/uuid.js b/lib/schema/uuid.js
index 1fbfc38654..6eb5d2f5ae 100644
--- a/lib/schema/uuid.js
+++ b/lib/schema/uuid.js
@@ -268,10 +268,10 @@ SchemaUUID.prototype.checkRequired = function checkRequired(value) {
  * @api private
  */
 
-SchemaUUID.prototype.cast = function(value, doc, init) {
+SchemaUUID.prototype.cast = function(value, doc, init, prev, options) {
   if (utils.isNonBuiltinObject(value) &&
       SchemaType._isRef(this, value, doc, init)) {
-    return this._castRef(value, doc, init);
+    return this._castRef(value, doc, init, options);
   }
 
   let castFn;
diff --git a/lib/schemaType.js b/lib/schemaType.js
index ed63c47bbc..d57cc775e6 100644
--- a/lib/schemaType.js
+++ b/lib/schemaType.js
@@ -1555,7 +1555,7 @@ SchemaType._isRef = function(self, value, doc, init) {
  * ignore
  */
 
-SchemaType.prototype._castRef = function _castRef(value, doc, init) {
+SchemaType.prototype._castRef = function _castRef(value, doc, init, options) {
   if (value == null) {
     return value;
   }
@@ -1587,7 +1587,7 @@ SchemaType.prototype._castRef = function _castRef(value, doc, init) {
     !doc.$__.populated[path].options.options ||
     !doc.$__.populated[path].options.options.lean) {
     const PopulatedModel = pop ? pop.options[populateModelSymbol] : doc.constructor.db.model(this.options.ref);
-    ret = new PopulatedModel(value);
+    ret = PopulatedModel.hydrate(value, null, options);
     ret.$__.wasPopulated = { value: ret._doc._id, options: { [populateModelSymbol]: PopulatedModel } };
   }
 
diff --git a/test/model.hydrate.test.js b/test/model.hydrate.test.js
index 447cc2be85..98ca46f0f7 100644
--- a/test/model.hydrate.test.js
+++ b/test/model.hydrate.test.js
@@ -198,5 +198,125 @@ describe('model', function() {
       assert.ok(c.populated('users'));
       assert.ok(c.users[0] instanceof User);
     });
+
+    it('marks deeply nested docs as hydrated underneath virtuals (gh-15110)', async function() {
+      const ArticleSchema = new Schema({ title: String });
+
+      const StorySchema = new Schema({
+        title: String,
+        userId: Schema.Types.ObjectId,
+        article: {
+          type: Schema.Types.ObjectId,
+          ref: 'Article'
+        }
+      });
+
+      const UserSchema = new Schema({
+        name: String
+      });
+
+      UserSchema.virtual('stories', {
+        ref: 'Story',
+        localField: '_id',
+        foreignField: 'userId'
+      });
+
+      db.deleteModel(/User/);
+      db.deleteModel(/Story/);
+      db.deleteModel(/Article/);
+      const User = db.model('User', UserSchema);
+      const Story = db.model('Story', StorySchema);
+      const Article = db.model('Article', ArticleSchema);
+      await Promise.all([
+        User.deleteMany({}),
+        Story.deleteMany({}),
+        Article.deleteMany({})
+      ]);
+
+      const article = await Article.create({ title: 'Cinema' });
+      const user = await User.create({ name: 'Alex' });
+      await Story.create({ title: 'Ticket 1', userId: user._id, article });
+      await Story.create({ title: 'Ticket 2', userId: user._id });
+
+      const populated = await User.findOne({ name: 'Alex' }).populate({
+        path: 'stories',
+        populate: ['article']
+      }).lean();
+
+      const hydrated = User.hydrate(
+        JSON.parse(JSON.stringify(populated)),
+        null,
+        { hydratedPopulatedDocs: true }
+      );
+
+      assert.ok(hydrated.populated('stories'));
+      assert.ok(hydrated.stories[0].populated('article'));
+      assert.equal(hydrated.stories[0].article._id.toString(), article._id.toString());
+      assert.ok(typeof hydrated.stories[0].article._id === 'object');
+      assert.ok(hydrated.stories[0].article._id instanceof mongoose.Types.ObjectId);
+      assert.equal(hydrated.stories[0].article.title, 'Cinema');
+
+      assert.ok(!hydrated.stories[1].article);
+    });
+
+    it('marks deeply nested docs as hydrated underneath conventional (gh-15110)', async function() {
+      const ArticleSchema = new Schema({
+        title: String
+      });
+
+      const StorySchema = new Schema({
+        title: String,
+        article: {
+          type: Schema.Types.ObjectId,
+          ref: 'Article'
+        }
+      });
+
+      const UserSchema = new Schema({
+        name: String,
+        stories: [{
+          type: Schema.Types.ObjectId,
+          ref: 'Story'
+        }]
+      });
+
+      db.deleteModel(/User/);
+      db.deleteModel(/Story/);
+      db.deleteModel(/Article/);
+      const User = db.model('User', UserSchema);
+      const Story = db.model('Story', StorySchema);
+      const Article = db.model('Article', ArticleSchema);
+      await Promise.all([
+        User.deleteMany({}),
+        Story.deleteMany({}),
+        Article.deleteMany({})
+      ]);
+
+      const article = await Article.create({ title: 'Cinema' });
+      const story1 = await Story.create({ title: 'Ticket 1', article });
+      const story2 = await Story.create({ title: 'Ticket 2' });
+
+      await User.create({ name: 'Alex', stories: [story1, story2] });
+
+      const populated = await User.findOne({ name: 'Alex' }).populate({
+        path: 'stories',
+        populate: ['article']
+      }).lean();
+
+      const hydrated = User.hydrate(
+        JSON.parse(JSON.stringify(populated)),
+        null,
+        { hydratedPopulatedDocs: true }
+      );
+
+      assert.ok(hydrated.populated('stories'));
+      assert.ok(hydrated.stories[0].populated('article'));
+      assert.equal(hydrated.stories[0].article._id.toString(), article._id.toString());
+      assert.ok(typeof hydrated.stories[0].article._id === 'object');
+      assert.ok(hydrated.stories[0].article._id instanceof mongoose.Types.ObjectId);
+      assert.equal(hydrated.stories[0].article.title, 'Cinema');
+
+      assert.ok(!hydrated.stories[1].article);
+    });
   });
 });