Display sub categories of one parent

I’ve spent some time searching and I know it’s easy to list the sub categories of a parent using wp_list_categories. What I’m trying to do is list only the sub category of a parent that is applied to a certain post. Say for example I have the following categories (children listed beneath the parent) set up:

Busline
-21
-16
-50

Type
-Funny
-Scary
-Smelly

A post is tagged with 21 and Scary. When displaying the post (on the home page and the single view) I want to show the location subcategory in one place and the type subcategory in another.

So the post would read something like this:

Route 21: Post Title
Content
Filed under scary

The site I’m working with is https://www.bustales.com and up until this point I’ve only used categories to assign the bus routes. I want to add in the type of story but I’m having trouble separating out the categories.

Thanks in advance.