This ship is from the two Titan shifters, Reiner Braun and Bertholdt Hoover. They never leave each other's side and are a very cute pairing. Bertholdt is also often seen around him and Reiner is his most trusted friend.
The Ship Name[]
The ship name comes from a part of Reiner's name Rei and a part of Bertholdt's name Bert. It's pretty obvious.
Uke and Seme[]
Berthold would be the Uke in the relationship and Reiner would obviously be the Seme. But, Bertholdt would only rarely be possessive and dominant to Reiner.
Extra[]
If you're a ReiBert fan, check out these stories:
https://www.fanfiction.net/s/11313404/1/Are-we-humans-Reiner-x-Bertolt