Representing relationships/hierarchy within an otherwise flat table view

I have a standard table view which is used in a number of places in an online cloud portal. It's used to list servers, products, firewalls and more.

As I begin to build views for the firewall listing specifically, I've realised there's a slight difference in relationships here. With firewalls in particular, I need to be able to not only list them but also indicate that certain pairs in the list are linked. Specifically, I need to be able to represent a Master/Slave relationship.

I have re-ordered the list so that these pairs always appear next to each other and have also included a text column which says Master/Slave. But I can't seem to find a good way to represent these relationships more clearly without breaking the portal's UX consistency and doing something crazy like indenting certain rows.