I assume by related that you want parent, sibling and child relationships.
A view to identify a parent can be provided by a view page defined with a path such as category/% where the % wildcard is a term's name. A relationship should be defined for the taxonomy term:parent. The view should expose whatever fields you want such as the term name, but leave the relationship dropdown box set to 'Do not use a relationship'. Set a contextual relationship for the term name and set the relationship dropdown as 'Parent'. (You must also set validation to a taxonomy term name so that the URL wildcard name will be interpreted correctly.
I answered this pretty thoroughly in this post.
Siblings: I worked at this one for a while before finding this post which suggests that it is not possible without the aid of Page manager. Sorry, but I was not able to find a way to do it with views alone.
My post uses D7 a V3 so there will be some differences in the UI to execute this, but I believe that the settings and basic configuration are the same with the exception that conceptual filters = arguments.