If you ever see the alpha legion they WANT you to see them usually followed by something horrible happening 3 systems over that Noone noticed
Having read a good number (not all) of the HH books, I have always liked how creepy the Alpha Legion were. Out of all the Traitor Legions, and in spite of the hilarious memes about them, the AL are the most disturbing to me.
I have a soft spot for the macabre degeneracy ans nihilism of the Night Lords, and I actually feel empathy for Fabius, but the Alpha Legion are the only ones who, whwn I've read about them, they've made me go: Oh now THAT is unnerving.
E.g. (spoilers) when Ingo Pech answers Grammaticus' questions in The End And The Death Vol 1. Calmly, albeit with a hint of almost paternal amusement.
An embodiment of that idiom that "the absence of evil does not mean one is good". They're not peeling off Grandma' skin, or beating Mum to death using Dad' body. But they're making moves... playing a long game...