He Does Not Deserve The Hate He Gets - Tumblr Posts

Keefe tried to kill Gisela-in-disguise-as-Cassius without any hesitation. Sophie punched Gethen with the Sucker Punch when he was tied up and posed no threat.

What makes Fitz's actions towards Alvar any different?

It's not the first time a character has tried to harm a family member. And Alvar posed a lot bigger of a threat to them at that time than Gethen did when Sophie punched him.

And also: Fitz tried multiple times to find ways to keep Alvar out of the fight without killing him. He tried to knock him out with an entirely harmless device. He tied him up. Even when the Neverseen was trying to goad him into killing Alvar, he told them he'd knock Alvar out instead of killing him.

Whether or not you think Fitz's actions were justified, he's not the only character to do something like this, and condemning him or saying that he's evil for this while ignoring similar actions by other characters is really unfair.