JSFiddle - React, Tailwind, and code Playground

JavaScript

var characters = [
  { 'name': 'barney', 'blocked': 'a', 'employer': 'slate' },
  { 'name': 'fred', 'blocked': 'a', 'employer': 'slate' },
  { 'name': 'pebbles', 'blocked': 'a', 'employer': 'na' },
  { 'name': 'pebbles', 'blocked': 'b', 'employer': 'hanna' },
  { 'name': 'wilma', 'blocked': 'c', 'employer': 'barbera' },
  { 'name': 'bam bam', 'blocked': 'c', 'employer': 'barbera' }
];
var a = _.filter(characters, { 'blocked': 'a' });
var b = _(characters)
            .difference(a)
            .reject(function (x) { 
                return _.where(a, { 'name': x.name }).length; 
            })
            .value();
console.log(b);