@Steven Gilliam  Sounds interesting, I believe your best option here is to have that information pulled into the account on the custom attribute level if you want to use it in the Series --- because then it will be readily available to any features of the Series. 

But I don’t work as deeply with Series on a day to day basis so there may be other ways to do custom actions etc that would work too but in my experience having the data brought in as custom attributes etc gives you the most flexibilty.  So if that data you wanted to fetch from the API was updated frequently in the attribute you’d be ready to go unless it’s changing so frequently that it would somehow be out of date due to the method you bring it in via the attribute. 

Hope this helps!