Friend of a Friend: Rendle and Cudgelface

In order to get this quest, you have to be invited to a friend's Ember Court scenario (you queue just like a normal party). Once in the scenario, after the setup time is complete, your friend should instantly complete the Ember Court scenario, putting it in the Afterparty phase.

Once in the Afterparty, you can collect this quest from Rendle and Cudgleface if the host of the Ember Court scenario has achieved Best Friend rank with them. If they are not Best Friends, you will not be offered the quest.

You can collect all of the guests' individual Friend of a Friend quests in one run of the Ember Court, as long as the host has the [item=177234] in their court. The bell is located in the tower you start out in, on the balcony- climb up, and the host must ring the bell. All Best Friends will then join the Afterparty, and you can get all the reputation bonuses in one go.

Good luck!

I would also like to give a small side note for all those completionist out there trying to 100% All the things. You cannot get the quest to pop up if you yourself have the friend at best friend status. The quest only pops up for players who do not have max rep for any of the friends in the ember court. We found out the hard way unfortunately. So yes if you need to get all those quests done you can only get them if you are in someone elses ember court (them having all them to best friend) while you on your side have not maxed their respective rep (friend level)