Frustrated by events in Iron Flame

Let me start off by saying I love this series. I wouldn't be on this sub if I didn't. It's exciting and fun and if there are parts that I skim through during rereads it's more because of impatience or with a fond eyeroll than with any sort of distaste. This is fantasy, and it's fantastic, and I embrace it all.

Except for one thing: Tairn allowing Varrish to live AT ALL.

I dont get it yall. Seriously. The whole of Fourth Wing establishes that humans don't command dragons. That dragons can kill you JUST FOR LOOKING AT THEM WRONG. Like, this is the basic, day 1 standard that is set and slammed into your brain over and over and over again. Dragons follow dragon rules and woe to any who get in their way.

So why does Varrish get to literally torture Violet for HALF A BOOK while Tairn does nothing?! We already know Tairn hates Solas. No worries about hurting a dragon buddy by killing his human there. We already know Tairn is a grumpy curmudgeon and that full grown veteran dragons tip toe around him for fear of checks notes THEIR LIVES. Much less how terrified humans are of the second biggest, deadliest, meanest dragon in existence (to the point where even Shadow Daddy Xaden, who is indirectly bonded to Tairn himself, is careful with how he speaks to him). But Varrish? A human?! Who tortures (even before the scheduled torture!) and threatens Violet, and threatens Tairn's (adopted) daughter Andarna? He gets a checks notes in absolute disbelief ROAR?! He gets a Solas headlock?! Why doesn't Tairn just kill him where he stands?!

I've reread this series so many times. I understand a lot of things, but this? I just don't get. It takes me out of suspended disbelief every single time. I try to justify it with the whole "we dont know the rules dragons have set in their own society so maybe he can't" thing but to me that reasoning flies out the window when >! Solas kills dozens of bonded riders from the jump !< . Make it make sense yall.