Big Sister
by Academia Nut (The author of
Thousand Shinji and
The Open Door) is a story with a similar premise to
Lovehammer: A
Magical Girl ends up in the
Warhammer 40000 universe before the Heresy and leaves a big mark. But the similarities end there.
When the future Primarch Vulkan arrives on Nocturne, he does not arrive alone, a teenaged girl, still recovering from crippling injuries even before somehow finding herself stranded on a
Death World, comes across the infant Primarch and brings him to the nearest settlement through sheer force of will.
The two grow up together as the girl recovers, eventually helping her little brother battle Dark Eldar Raiders. The girl takes the nickname of Ga’ri, meaning "Ash Maiden", a name she finds fitting, despite the sometime negative connotations that come with it. As she regains the use of her magic, Ga’ri also helps her "Little Brother" grow in mind and spirit as fast as he does in body. When The Emperor lands on Nocturne, he finds his lost son to be a very different man than even he was expecting.