exchange.js

function getRandom(max) {
  return Math.floor(Math.random() * Math.floor(max));
}

let input = ['Tyrion', 'Daenerys', 'Bronn', 'Margaery', 'Brienne'];
let output = '';

let gives = [...input];
let receives = [...input];
let giverObj = {};

while(gives.length > 1){
	let giver = getRandom(gives.length);
  let giverStr = gives[giver];

  let receiver = getRandom(receives.length);
  let receiverStr = receives[receiver];

  if(giverStr === receiverStr || giverObj[receiverStr] === giverStr) {
    continue;
  }

  giverObj[receiverStr] = giverStr;
  receives.splice(receiver, 1);
  gives.splice(giver, 1);
  
  output += `${giverStr} passes to ${receiverStr}, `;
}

output += `${gives[0]} passes to ${receives[0]}`;


console.log(output);