diff --git a/includes/collection/class-interactions.php b/includes/collection/class-interactions.php
new file mode 100644
index 0000000..42fdcfe
--- /dev/null
+++ b/includes/collection/class-interactions.php
@@ -0,0 +1,133 @@
+<?php
+namespace Activitypub\Collection;
+
+use WP_Error;
+
+use function Activitypub\object_id_to_comment;
+use function Activitypub\get_remote_metadata_by_actor;
+
+/**
+ * ActivityPub Interactions Collection
+ */
+class Interactions {
+	/**
+	 * Add a comment to a post
+	 *
+	 * @param array $activity The activity-object
+	 *
+	 * @return array|false The commentdata or false on failure
+	 */
+	public static function add_comment( $activity ) {
+		if (
+			! isset( $activity['object'] ) ||
+			! isset( $activity['object']['id'] )
+		) {
+			return new WP_Error(
+				'activitypub_no_valid_object',
+				__( 'No object id found.', 'activitypub' ),
+				array( 'status' => 400 )
+			);
+		}
+
+		if ( ! isset( $activity['object']['inReplyTo'] ) ) {
+			return new WP_Error(
+				'activitypub_no_reply',
+				__( 'Object is no reply.', 'activitypub' ),
+				array( 'status' => 400 )
+			);
+		}
+
+		$in_reply_to     = \esc_url_raw( $activity['object']['inReplyTo'] );
+		$comment_post_id = \url_to_postid( $in_reply_to );
+		$parent_comment  = object_id_to_comment( $in_reply_to );
+
+		// save only replys and reactions
+		if ( ! $comment_post_id && $parent_comment ) {
+			$comment_post_id = $parent_comment->comment_post_ID;
+		}
+
+		// not a reply to a post or comment
+		if ( ! $comment_post_id ) {
+			return new WP_Error(
+				'activitypub_no_reply',
+				__( 'Object is no reply.', 'activitypub' ),
+				array( 'status' => 400 )
+			);
+		}
+
+		$meta = get_remote_metadata_by_actor( $activity['actor'] );
+
+		if ( ! $meta || \is_wp_error( $meta ) ) {
+			return new WP_Error(
+				'activitypub_invalid_follower',
+				__( 'Invalid Follower', 'activitypub' ),
+				array( 'status' => 400 )
+			);
+		}
+
+		$commentdata = array(
+			'comment_post_ID' => $comment_post_id,
+			'comment_author' => \esc_attr( $meta['name'] ),
+			'comment_author_url' => \esc_url_raw( $meta['url'] ),
+			'comment_content' => addslashes( \wp_kses( $activity['object']['content'], 'pre_comment_content' ) ),
+			'comment_type' => 'comment',
+			'comment_author_email' => '',
+			'comment_parent' => $parent_comment ? $parent_comment->comment_ID : 0,
+			'comment_meta' => array(
+				'source_id'  => \esc_url_raw( $activity['object']['id'] ),
+				'source_url' => \esc_url_raw( $activity['object']['url'] ),
+				'avatar_url' => \esc_url_raw( $meta['icon']['url'] ),
+				'protocol'   => 'activitypub',
+			),
+		);
+
+		// disable flood control
+		\remove_action( 'check_comment_flood', 'check_comment_flood_db', 10 );
+
+		// do not require email for AP entries
+		\add_filter( 'pre_option_require_name_email', '__return_false' );
+		// No nonce possible for this submission route
+		\add_filter(
+			'akismet_comment_nonce',
+			function() {
+				return 'inactive';
+			}
+		);
+		\add_filter( 'wp_kses_allowed_html', array( self::class, 'allowed_comment_html' ), 10, 2 );
+
+		$comment = \wp_new_comment( $commentdata, true );
+
+		\remove_filter( 'wp_kses_allowed_html', array( self::class, 'allowed_comment_html' ), 10 );
+		\remove_filter( 'pre_option_require_name_email', '__return_false' );
+
+		// re-add flood control
+		\add_action( 'check_comment_flood', 'check_comment_flood_db', 10, 4 );
+
+		return $comment;
+	}
+
+	/**
+	 * Adds line breaks to the list of allowed comment tags.
+	 *
+	 * @param  array  $allowedtags Allowed HTML tags.
+	 * @param  string $context     Context.
+	 * @return array               Filtered tag list.
+	 */
+	public static function allowed_comment_html( $allowedtags, $context = '' ) {
+		if ( 'pre_comment_content' !== $context ) {
+			// Do nothing.
+			return $allowedtags;
+		}
+
+		// Add `p` and `br` to the list of allowed tags.
+		if ( ! array_key_exists( 'br', $allowedtags ) ) {
+			$allowedtags['br'] = array();
+		}
+
+		if ( ! array_key_exists( 'p', $allowedtags ) ) {
+			$allowedtags['p'] = array();
+		}
+
+		return $allowedtags;
+	}
+}
diff --git a/includes/handler/class-create.php b/includes/handler/class-create.php
index f2d2929..40fffcd 100644
--- a/includes/handler/class-create.php
+++ b/includes/handler/class-create.php
@@ -1,8 +1,11 @@
 <?php
 namespace Activitypub\Handler;
 
+use WP_Error;
+use Activitypub\Collection\Interactions;
+
 use function Activitypub\is_activity_public;
-use function Activitypub\get_remote_metadata_by_actor;
+use function Activitypub\object_id_to_comment;
 
 /**
  * Handle Create requests
@@ -12,108 +15,59 @@ class Create {
 	 * Initialize the class, registering WordPress hooks
 	 */
 	public static function init() {
-		\add_action( 'activitypub_inbox_create', array( self::class, 'handle_create' ), 10, 2 );
+		\add_action( 'activitypub_inbox_create', array( self::class, 'handle_create' ), 10, 3 );
 	}
 
 	/**
 	 * Handles "Create" requests
 	 *
-	 * @param  array $activity  The activity-object
-	 * @param  int   $user_id The id of the local blog-user
+	 * @param array                $array   The activity-object
+	 * @param int                  $user_id The id of the local blog-user
+	 * @param Activitypub\Activity $object  The activity object
+	 *
+	 * @return void|WP_Error WP_Error on failure
 	 */
-	public static function handle_create( $activity, $user_id ) {
-		$meta = get_remote_metadata_by_actor( $activity['actor'] );
-
-		if ( ! isset( $activity['object']['inReplyTo'] ) ) {
-			return;
+	public static function handle_create( $array, $user_id, $object = null ) {
+		if (
+			! isset( $array['object'] ) ||
+			! isset( $array['object']['id'] )
+		) {
+			return new WP_Error(
+				'activitypub_no_valid_object',
+				__( 'No object id found.', 'activitypub' ),
+				array( 'status' => 400 )
+			);
 		}
 
 		// check if Activity is public or not
-		if ( ! is_activity_public( $activity ) ) {
+		if ( ! is_activity_public( $array ) ) {
 			// @todo maybe send email
-			return;
+			return new WP_Error(
+				'activitypub_activity_not_public',
+				__( 'Activity is not public.', 'activitypub' ),
+				array( 'status' => 400 )
+			);
 		}
 
-		$comment_post_id = \url_to_postid( $activity['object']['inReplyTo'] );
+		$check_dupe = object_id_to_comment( $array['object']['id'] );
 
-		// save only replys and reactions
-		if ( ! $comment_post_id ) {
-			return false;
+		// if comment exists, call update action
+		if ( $check_dupe ) {
+			\do_action( 'activitypub_inbox_update', $array, $user_id, $object );
+			return new WP_Error(
+				'activitypub_comment_exists',
+				__( 'Comment already exists, initiated Update process.', 'activitypub' ),
+				array( 'status' => 400 )
+			);
 		}
 
-		$commentdata = array(
-			'comment_post_ID' => $comment_post_id,
-			'comment_author' => \esc_attr( $meta['name'] ),
-			'comment_author_url' => \esc_url_raw( $activity['actor'] ),
-			'comment_content' => \wp_filter_kses( $activity['object']['content'] ),
-			'comment_type' => 'comment',
-			'comment_author_email' => '',
-			'comment_parent' => 0,
-			'comment_meta' => array(
-				'source_id' => \esc_url_raw( $activity['object']['id'] ),
-				'source_url' => \esc_url_raw( $activity['object']['url'] ),
-				'avatar_url' => \esc_url_raw( $meta['icon']['url'] ),
-				'protocol' => 'activitypub',
-			),
-		);
+		$reaction = Interactions::add_comment( $array );
+		$state    = null;
 
-		// disable flood control
-		\remove_action( 'check_comment_flood', 'check_comment_flood_db', 10 );
-
-		// do not require email for AP entries
-		\add_filter( 'pre_option_require_name_email', '__return_false' );
-
-		// No nonce possible for this submission route
-		\add_filter(
-			'akismet_comment_nonce',
-			function() {
-				return 'inactive';
-			}
-		);
-
-		$state = \wp_new_comment( $commentdata, true );
-
-		\remove_filter( 'pre_option_require_name_email', '__return_false' );
-
-		// re-add flood control
-		\add_action( 'check_comment_flood', 'check_comment_flood_db', 10, 4 );
-
-		\do_action( 'activitypub_handled_create', $activity, $user_id, $state, $commentdata );
-	}
-
-	/**
-	 * Handles "Create" requests
-	 *
-	 * @param  array $object  The activity-object
-	 * @param  int   $user_id The id of the local blog-user
-	 */
-	public static function handle_create_alt( $object, $user_id ) {
-		$commentdata = self::convert_object_to_comment_data( $object, $user_id );
-		if ( ! $commentdata ) {
-			return false;
+		if ( $reaction ) {
+			$state = $reaction['comment_ID'];
 		}
 
-		// disable flood control
-		\remove_action( 'check_comment_flood', 'check_comment_flood_db', 10 );
-
-		// do not require email for AP entries
-		\add_filter( 'pre_option_require_name_email', '__return_false' );
-
-		// No nonce possible for this submission route
-		\add_filter(
-			'akismet_comment_nonce',
-			function() {
-				return 'inactive';
-			}
-		);
-
-		$state = \wp_new_comment( $commentdata, true );
-
-		\remove_filter( 'pre_option_require_name_email', '__return_false' );
-
-		// re-add flood control
-		\add_action( 'check_comment_flood', 'check_comment_flood_db', 10, 4 );
-
-		do_action( 'activitypub_handled_create', $object, $user_id, $state, $commentdata );
+		\do_action( 'activitypub_handled_create', $array, $user_id, $state, $reaction );
 	}
 }
diff --git a/includes/handler/class-delete.php b/includes/handler/class-delete.php
index a33ffdd..893ccf9 100644
--- a/includes/handler/class-delete.php
+++ b/includes/handler/class-delete.php
@@ -12,6 +12,7 @@ class Delete {
 	 */
 	public static function init() {
 		\add_action( 'activitypub_inbox_delete', array( self::class, 'handle_delete' ), 10, 2 );
+		//
 	}
 
 	/**
@@ -42,6 +43,8 @@ class Delete {
 					$follower->delete();
 				}
 
+				// delete all activities from this user.
+
 				break;
 			case 'Tombstone':
 				// Handle tombstone.
diff --git a/tests/test-class-activitypub-create-handler.php b/tests/test-class-activitypub-create-handler.php
new file mode 100644
index 0000000..4cf2fea
--- /dev/null
+++ b/tests/test-class-activitypub-create-handler.php
@@ -0,0 +1,70 @@
+<?php
+class Test_Activitypub_Create_Handler extends WP_UnitTestCase {
+	public $user_id;
+	public $user_url;
+	public $post_id;
+	public $post_permalink;
+
+	public function set_up() {
+		$this->user_id = 1;
+		$authordata = \get_userdata( $this->user_id );
+		$this->user_url = $authordata->user_url;
+
+		$this->post_id = \wp_insert_post(
+			array(
+				'post_author' => $this->user_id,
+				'post_content' => 'test',
+			)
+		);
+		$this->post_permalink = \get_permalink( $this->post_id );
+
+		\add_filter( 'pre_get_remote_metadata_by_actor', array( '\Test_Activitypub_Create_Handler', 'get_remote_metadata_by_actor' ), 0, 2 );
+	}
+
+	public static function get_remote_metadata_by_actor( $value, $actor ) {
+		return array(
+			'name' => 'Example User',
+			'icon' => array(
+				'url' => 'https://example.com/icon',
+			),
+			'url'  => $actor,
+			'id'   => 'http://example.org/users/example',
+		);
+	}
+
+	public function create_test_object( $id = 'https://example.com/123' ) {
+		return array(
+			'actor' => $this->user_url,
+			'id' => 'https://example.com/id/' . microtime( true ),
+			'to' => [ $this->user_url ],
+			'cc' => [ 'https://www.w3.org/ns/activitystreams#Public' ],
+			'object' => array(
+				'id'        => $id,
+				'url'       => 'https://example.com/example',
+				'inReplyTo' => $this->post_permalink,
+				'content'   => 'example',
+			),
+		);
+	}
+
+	public function test_handle_create_object_unset_rejected() {
+		$object = $this->create_test_object();
+		unset( $object['object'] );
+		$converted = Activitypub\Handler\Create::handle_create( $object, $this->user_id );
+		$this->assertEquals( $converted->get_error_code(), 'activitypub_no_valid_object' );
+	}
+
+	public function test_handle_create_non_public_rejected() {
+		$object = $this->create_test_object();
+		$object['cc'] = [];
+		$converted = Activitypub\Handler\Create::handle_create( $object, $this->user_id );
+		$this->assertEquals( $converted->get_error_code(), 'activitypub_activity_not_public' );
+	}
+
+	public function test_handle_create_no_id_rejected() {
+		$object = $this->create_test_object();
+		unset( $object['object']['id'] );
+		$converted = Activitypub\Handler\Create::handle_create( $object, $this->user_id );
+		$this->assertEquals( $converted->get_error_code(), 'activitypub_no_valid_object' );
+	}
+}
diff --git a/tests/test-class-db-activitypub-followers.php b/tests/test-class-activitypub-followers.php
similarity index 99%
rename from tests/test-class-db-activitypub-followers.php
rename to tests/test-class-activitypub-followers.php
index 8fc0068..8b00d19 100644
--- a/tests/test-class-db-activitypub-followers.php
+++ b/tests/test-class-activitypub-followers.php
@@ -1,5 +1,5 @@
 <?php
-class Test_Db_Activitypub_Followers extends WP_UnitTestCase {
+class Test_Activitypub_Followers extends WP_UnitTestCase {
 	public static $users = array(
 		'username@example.org' => array(
 			'id' => 'https://example.org/users/username',
diff --git a/tests/test-class-activitypub-interactions.php b/tests/test-class-activitypub-interactions.php
new file mode 100644
index 0000000..1767b1f
--- /dev/null
+++ b/tests/test-class-activitypub-interactions.php
@@ -0,0 +1,112 @@
+<?php
+class Test_Activitypub_Interactions extends WP_UnitTestCase {
+	public $user_id;
+	public $user_url;
+	public $post_id;
+	public $post_permalink;
+
+	public function set_up() {
+		$this->user_id = 1;
+		$authordata = \get_userdata( $this->user_id );
+		$this->user_url = $authordata->user_url;
+
+		$this->post_id = \wp_insert_post(
+			array(
+				'post_author' => $this->user_id,
+				'post_content' => 'test',
+			)
+		);
+		$this->post_permalink = \get_permalink( $this->post_id );
+
+		\add_filter( 'pre_get_remote_metadata_by_actor', array( '\Test_Activitypub_Interactions', 'get_remote_metadata_by_actor' ), 0, 2 );
+	}
+
+	public static function get_remote_metadata_by_actor( $value, $actor ) {
+		return array(
+			'name' => 'Example User',
+			'icon' => array(
+				'url' => 'https://example.com/icon',
+			),
+			'url'  => $actor,
+			'id'   => 'http://example.org/users/example',
+		);
+	}
+
+	public function create_test_object( $id = 'https://example.com/123' ) {
+		return array(
+			'actor' => $this->user_url,
+			'id' => 'https://example.com/id/' . microtime( true ),
+			'to' => [ $this->user_url ],
+			'cc' => [ 'https://www.w3.org/ns/activitystreams#Public' ],
+			'object' => array(
+				'id'        => $id,
+				'url'       => 'https://example.com/example',
+				'inReplyTo' => $this->post_permalink,
+				'content'   => 'example',
+			),
+		);
+	}
+
+	public function test_handle_create_basic() {
+		$comment_id = Activitypub\Collection\Interactions::add_comment( $this->create_test_object() );
+		$comment   = get_comment( $comment_id, ARRAY_A );
+
+		$this->assertIsArray( $comment );
+		$this->assertEquals( $this->post_id, $comment['comment_post_ID'] );
+		$this->assertEquals( 'Example User', $comment['comment_author'] );
+		$this->assertEquals( $this->user_url, $comment['comment_author_url'] );
+		$this->assertEquals( 'example', $comment['comment_content'] );
+		$this->assertEquals( 'comment', $comment['comment_type'] );
+		$this->assertEquals( '', $comment['comment_author_email'] );
+		$this->assertEquals( 0, $comment['comment_parent'] );
+		$this->assertEquals( 'https://example.com/123', get_comment_meta( $comment_id, 'source_id', true ) );
+		$this->assertEquals( 'https://example.com/example', get_comment_meta( $comment_id, 'source_url', true ) );
+		$this->assertEquals( 'https://example.com/icon', get_comment_meta( $comment_id, 'avatar_url', true ) );
+		$this->assertEquals( 'activitypub', get_comment_meta( $comment_id, 'protocol', true ) );
+	}
+
+	public function test_convert_object_to_comment_not_reply_rejected() {
+		$object = $this->create_test_object();
+		unset( $object['object']['inReplyTo'] );
+		$converted = Activitypub\Collection\Interactions::add_comment( $object );
+		$this->assertEquals( $converted->get_error_code(), 'activitypub_no_reply' );
+	}
+
+	public function test_convert_object_to_comment_already_exists_rejected() {
+		$object = $this->create_test_object( 'https://example.com/test_convert_object_to_comment_already_exists_rejected' );
+		Activitypub\Collection\Interactions::add_comment( $object );
+		$converted = Activitypub\Collection\Interactions::add_comment( $object );
+		$this->assertEquals( $converted->get_error_code(), 'comment_duplicate' );
+	}
+
+	public function test_convert_object_to_comment_reply_to_comment() {
+		$id = 'https://example.com/test_convert_object_to_comment_reply_to_comment';
+		$object = $this->create_test_object( $id );
+		Activitypub\Collection\Interactions::add_comment( $object );
+		$comment = \Activitypub\object_id_to_comment( $id );
+
+		$object['object']['inReplyTo'] = $id;
+		$object['object']['id'] = 'https://example.com/234';
+		$id = Activitypub\Collection\Interactions::add_comment( $object );
+		$converted = get_comment( $id, ARRAY_A );
+
+		$this->assertIsArray( $converted );
+		$this->assertEquals( $this->post_id, $converted['comment_post_ID'] );
+		$this->assertEquals( $comment->comment_ID, $converted['comment_parent'] );
+	}
+
+	public function test_convert_object_to_comment_reply_to_non_existent_comment_rejected() {
+		$object = $this->create_test_object();
+		$object['object']['inReplyTo'] = 'https://example.com/not_found';
+		$converted = Activitypub\Collection\Interactions::add_comment( $object );
+		$this->assertEquals( $converted->get_error_code(), 'activitypub_no_reply' );
+	}
+
+	public function test_handle_create_basic2() {
+		$id = 'https://example.com/test_handle_create_basic';
+		$object = $this->create_test_object( $id );
+		Activitypub\Collection\Interactions::add_comment( $object );
+		$comment = \Activitypub\object_id_to_comment( $id );
+		$this->assertInstanceOf( WP_Comment::class, $comment );
+	}
+}