One great Black Rock Shooter x Dead Master fanfiction is 'The Bond Beyond Battle'. It delves deep into their complex relationship, exploring how they might interact outside of combat scenarios. The story shows their growth as characters and how their bond could develop over time.
There's also 'A Different Perspective' which offers a unique take on their relationship. It portrays Dead Master in a more sympathetic light, and the interactions between her and Black Rock Shooter are filled with a lot of emotional depth. This fanfiction really makes you think about their true connection.
Well, 'The Meeting of Souls' is a popular one too. In this fanfiction, it focuses on a chance encounter between Black Rock Shooter and Dead Master that sets off a series of events that change both of them. It has some really interesting plot twists and the characterizations are on point.