Given that we were told that we'd have no reason to sympathise with Zenos, I'm inclined to believe that he's simply a bad apple. Garlemald values might, certainly, though to a large degree that is out of necessity - Hydaelyn isn't the greatest place to live to begin with and Garlemald's inner territory is a frigid wasteland. Zenos was afforded a life of relative luxury - and it doesn't appear that Varis deliberately went out of his way to nurture Zenos' monstrous nature. In fact, he outright opposed it - just as he opposed Aulus and sent him packing. There's also the possibility that Zenos was compromised by Elidibus and/or Solus and that Zenos being used as a host for Elidibus was planned from the very start of his conception - and that is the sort of thing I do not see Varis approving of at all.

The snippets of the lore book imply that Varis has multiple heirs. If they're still alive or we get further elaboration then how they turned out will be a good way to judge Varis' capabilities as a father figure. He's not exactly emotionless - and the fact that his friendship with Regula spanned decades without wavering suggests that he is capable of long term affection.