A lot of things.

app/Models/Author.php

@@ -2,11 +2,29 @@
 
 namespace App\Models;
 
+use App\Auth\XenForoUser;
+use App\Services\XenforoService;
 use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsToMany;
+use Illuminate\Database\Eloquent\Relations\HasMany;
 
 class Author extends Model
 {
     protected $fillable = [
         'name', 'slug', 'user_id', 'website'
     ];
+
+    public function entries(): BelongsToMany
+    {
+        return $this->belongsToMany(Entry::class, 'entry_authors');
+    }
+
+    public function user(): ?XenForoUser
+    {
+        if( !$this->user_id )
+            return null;
+
+        return app(XenforoService::class)->getXfUser($this->user_id);
+    }
+
 }