The news hadn't been kept secret for long, Vulkan was grateful that it had been like that
Just a couple of months ago, he, and probably most of his brothers, had learned of the presence of a new 'Astarte' in the Night Lords Legion. At first, many might think, well, it wasn't anything new; the legions were always recruiting more and all that, but what this Astarte was peculiar: he was taller than the rest, much taller than the rest of the Astartes in the Night Lords Legion. That was the first curiosity.
The second curiosity came when it could be noticed, in a certain strange way, that Konrad did not look as disgusted with this Astarte as he did with the others, it was well known that The Night Hunter hated his legion with his soul
And possibly the third curiosity that spilled the glass of uncertainty was the fact that Malcador the Sigillite, the Emperor's right-hand man and the closest thing the Primarchs had to an "uncle", was communicative with this Astarte, something never before seen between Malcador the Sigillite and a legionary of the Night Lords. Since the man and the legionaries of the VIII, the Night Lords, used to have an antagonistic relationship
It wasn't until later, in a campaign in which the Salamanders and the Night Lords had to work together, that the truth was revealed to Vulkan. This legionary, strangely taller than the rest, was biologically fathered by Konrad. This news left a bitter taste in his mouth and even more intrigue and concern, although he didn't show it openly physically.
Vulkan only felt sympathy for the poor devil who had to be born from Konrad and the poor woman who had to endure such punishment
But the damage was done, Vulkan was now an uncle. He knew he couldn't judge anyone without knowing them. Perhaps this child of Konrad's was different? Perhaps calmer?. Vulkan tried not to jump to conclusions; he couldn't blame the child for the father's actions and crimes. He would try to get to know his nephew, and then decide whether or not it was necessary to worry... although he would have liked for that child to grow up in a better place, any place in general was better than with the VIII legion
The battlefield was being cleared, another battle, on another distant, abandoned planet. The Night Lords had made a mess, and now Vulkan and his legion had to clean up that mess, harvest gene seeds from his fallen sons, and so on. The usual, plus the Night Lords' unappreciated participation.
Vulkan stood, watching the dust of battle settle