If kindred is the circle of people closest to you, kithren is the next circle out: good friends!
The word kith comes from Old English and means those that you know well. In The Assemblage of Areté we use the term kith to specifically refer to small fellowshipping groups that all members get called to join. These small groups take on fun names, like “Kith Phoenix” or “Kith Seahorse” and wear badges to show pride in their kith, similar to showing pride in a team. Members of a kith will meet together as often as it works for them to do so, to do fun activities together and become better friends with one another!