And hint is Ventanus having a blue snake as his chosen iconography.
What Graham McNeil does is base plots around his 40K books.
I'm not a big fan of McNeil's, but you're mixing up your authors here. It's Saur Damocles who has the "figure-of-eight serpent emblem", and the tie-in there is between Abnett's Know No Fear
and Brothers of the Snake.
Mileage will obviously vary on how much a reader might like this sort of tie-in, but I was happy to see a Chapter's hitherto unknown origins revealed.