This video of kawaii Space Marines is canon, actually
I know very little about Warhammer 40,000. I know it chiefly as a very expensive way to sit in a shop and move little figurines around on a Saturday, which in my youth I had neither the income nor self-confidence to try. I have a number of friends and colleagues who understand it on a foundational level, though, and they assure me that one of the benefits of the setting is that by lining up enough of the vast number of bizarre and bombastic parameters by which it operates, and squinting at them with sufficient determination, you can assemble a robust enough headcanon to justify pretty much any scenario you can imagine.
The best example of this I have been presented with is the fan reaction to the 2023’s Boltgun, which gave Warhammer 40k the boomer shooter treatment. In it, Space Marine protagonist Malum Caedo carves an implausibly bloody swathe through continental quantities of opponents while shouting instead of breathing. This is, I was assured, emphatically in line with the job description of the genetically enhanced warriors of the Adeptus Astartes - but even the most hardbitten tabletop Space Marine player would need an implausible number of perfect