There should be some easy way right? How else is the category page getting the child categories as well? It's basically on the category page and I want to get the sub categories of a subcategory on the category page. So i have this category ID, so I should get the subcategories fairly easy right?
Found it:
$categoryModel= VmModel::getModel('category');
$categoryChildren = $categoryModelTemp->getChildCategoryList(0, $category->virtuemart_category_id);