Крис Райт очень подробно рассказал и о Тринадцатой, и о терранцах, и о фенрисийцах. Просто прочитайте его роман, и будет вам счастье :)
The jarl of Tra was a pure-bred Fenrisian, with the distended jaw-line, the thick hair, the amber eyes to act as his markers. He had been among the first of the youths to take the terrible draught out in the wilds of Asaheim, but not the first of the Legion. Terrans had been in the ranks for decades, and after that had come the primarch's own followers, the retainers of the Hall of King Leman Russ. Now those last were the greybeards, called the 'Wolf Brothers', all members of the Thirteenth Great Company, dwindling in number with every year as the rigours of endless war took their toll.
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'You thought it was Dekk-Tra, the Thirteenth, alone,' said Russ, bitterly. 'You thought you had the fault within you, and none other suffered. You were wrong. It will be worse for you, perhaps, but we all carry it. It is what we hear in the chill of the night, when the sounds of war are banished and all we have left is ourselves. Best to keep fighting, eh? Never have to hear it, then.'
Russ drew closer to his jarl, reaching out for him with both hands, seizing him by the shoulders and dragging him closer.
'And I did not want to think it,' he breathed, so softly that only the two of them heard the words. 'You, above all, you. When I saw you pass the test, when the Terrans told me it was impossible, my hearts leapt, for I knew that I could trust my shield-bearer in all things. None, I told myself, none of Terra or Fenris, would match you. All others would fail me, in the end, but not you, for we were both of the same hall, and Thengir was our sire, and we had trod the ice together before there was anything else.'