diff --git a/src/gradient_labs/_article_set_status.py b/src/gradient_labs/_article_set_status.py
index bc674ea..c2e0241 100644
--- a/src/gradient_labs/_article_set_status.py
+++ b/src/gradient_labs/_article_set_status.py
@@ -1,12 +1,7 @@
-from typing import Optional, Any
-from collections import defaultdict
-from datetime import datetime
+from dataclasses import dataclass
+from dataclasses_json import dataclass_json
 
-from dataclasses import dataclass, field
-from dataclasses_json import dataclass_json, config
-from marshmallow import fields
-
-from .article import Visibility, PublicationStatus, ArticleUsageStatus
+from .article import ArticleUsageStatus
 from ._http_client import HttpClient
 
 
diff --git a/src/gradient_labs/_article_topic_upsert.py b/src/gradient_labs/_article_topic_upsert.py
index 1165e6b..35c9650 100644
--- a/src/gradient_labs/_article_topic_upsert.py
+++ b/src/gradient_labs/_article_topic_upsert.py
@@ -7,7 +7,6 @@
 from marshmallow import fields
 
 from .article import Visibility, PublicationStatus
-
 from ._http_client import HttpClient
 
 
@@ -17,15 +16,9 @@ class ArticleTopicUpsertParams:
     # id is your identifier for this topic
     id: str
 
-    # parent_id is the identifier for this topic's parent topic (if any).
-    parent_id: str
-
     # name is the topic's name. This cannot be empty.
     name: str
 
-    # description is an topic's tagline. It may be empty.
-    description: str
-
     # visibility describes who can see this topic, ranging from the
     # whole world (public) through to employees only (internal).
     visibility: Visibility
@@ -51,6 +44,12 @@ class ArticleTopicUpsertParams:
         )
     )
 
+    # description is an topic's tagline. It may be empty.
+    description: Optional[str] = None
+
+    # parent_id is the identifier for this topic's parent topic (if any).
+    parent_id: Optional[str] = None
+
     # data optionally gives additional meta-data about the topic.
     data: Optional[dict] = field(default_factory=lambda: defaultdict(dict))
 
@@ -58,4 +57,15 @@ class ArticleTopicUpsertParams:
 def upsert_article_topic(
     *, client: HttpClient, params: ArticleTopicUpsertParams
 ) -> None:
-    _ = client.post(path="topics", body=params.to_dict())
+    body = params.to_dict()
+    if params.parent_id is None:
+        body.pop("parent_id")
+    if params.description is None:
+        body.pop("description")
+    
+    body["created"] = HttpClient.localize(params.created)
+    body["last_edited"] = HttpClient.localize(params.last_edited)
+    _ = client.post(
+        path="topics",
+        body=body,
+    )
diff --git a/src/gradient_labs/_article_upsert.py b/src/gradient_labs/_article_upsert.py
index 60d4666..2d397eb 100644
--- a/src/gradient_labs/_article_upsert.py
+++ b/src/gradient_labs/_article_upsert.py
@@ -13,30 +13,14 @@
 @dataclass_json
 @dataclass(frozen=True)
 class UpsertArticleParams:
-    # author_id optionally identifies the user who last edited the article
-    author_id: str
 
     # id is your identifier of choice for this article.
     id: str
 
-    # title is the article's title. It may be empty if the article is a draft.
-    title: str
-
-    # description is an article's tagline. It may be empty.
-    description: str
-
-    # body is the main contents of an article. It may be empty if the article is a draft.
-    body: str
-
     # visibility describes who can access this article, ranging from the
     # whole world (public) through to employees only (internal).
     visibility: Visibility
 
-    # topic_id optionally identifies the topic that this
-    # article is associated with. If given, you must have created
-    # the topic first (see: UpsertArticleTopic)
-    topic_id: str
-
     # status describes whether this article is published or not.
     status: PublicationStatus
 
@@ -58,12 +42,43 @@ class UpsertArticleParams:
         )
     )
 
+    # topic_id optionally identifies the topic that this
+    # article is associated with. If given, you must have created
+    # the topic first (see: UpsertArticleTopic)
+    topic_id: Optional[str] = None
+
+    # author_id optionally identifies the user who last edited the article
+    author_id: Optional[str] = None
+
+    # title is the article's title. It may be empty if the article is a draft.
+    title: Optional[str] = None
+
+    # description is an article's tagline. It may be empty.
+    description: Optional[str] = None
+
+    # body is the main contents of an article. It may be empty if the article is a draft.
+    body: Optional[str] = None
+
     # data optionally gives additional meta-data about the article.
     data: Optional[Any] = field(default_factory=lambda: defaultdict(dict))
 
 
 def upsert_article(*, client: HttpClient, params: UpsertArticleParams) -> None:
+    body = params.to_dict()
+    if params.title is None:
+        body.pop("title")
+    if params.description is None:
+        body.pop("description")
+    if params.topic_id is None:
+        body.pop("topic_id")
+    if params.author_id is None:
+        body.pop("author_id")
+    if params.body is None:
+        body.pop("body")
+    
+    body["created"] = HttpClient.localize(params.created)
+    body["last_edited"] = HttpClient.localize(params.last_edited)
     _ = client.post(
         path="articles",
-        body=params.to_dict(),
+        body=body,
     )
diff --git a/src/gradient_labs/errors.py b/src/gradient_labs/errors.py
index 7b7cefe..497e567 100644
--- a/src/gradient_labs/errors.py
+++ b/src/gradient_labs/errors.py
@@ -1,4 +1,5 @@
-from json import JSONDecodeError
+from requests.exceptions import JSONDecodeError
+
 
 class ResponseError(Exception):
     """