ReiBert

ReiBert is the slash ship between Reiner Braun and Bertolt Hoover from the Attack on Titan fandom.

Canon
In childhood, Reiner and Bertolt trained together as Warrior candidates. Bertolt was seemingly the only one who was nice to Reiner, comforting him whenever he was bullied by Porco.

The two of them stuck by each other during their time on Paradis Island. Bertolt saved Reiner from a titan at Utgard Castle and, during their mission to kidnap Eren, Reiner protected Bertolt in his titan form. Bertolt always trusted in Reiner's decisions but also showed deep concern for his mental stability and split personality.

Fandom
AO3