Tiştên Negotî (Words Not Needed)
From Shousetsu Bang*Bang Wiki
Tiştên Negotî (Words Not Needed) is a story written by natsumachi and illustrated by beili. It ran in Issue 48 and can be read at LJ and the S2B2 website.
The title is in Kurmanci dialect of Kurdish, and more literally means "things unsaid (by you)".
Summary
A young man pines for the man who has cared for him and been his rock since he was younger. Teasing, nostalgia, and phone sex. The setting is modern or near future, though not necessarily in a realistic contemporary world.
Connections
Tiştên Negotî has no connecting stories published in S2B2.
It's not particularly secret that the story has its roots in AU fanfiction. And fans of a certain giant robot anime might notice the references.