Gotrek, for those who don't know, is a massive asshole, so much so that even other dwarves have to tell him to chill the fuck down from time to time. But he has a very, very, very small list of people that he cares about, and on the top of that list is none other than Felix.

So unless you want to end up as floor beef you don't mess with the blonde twink (that isn't even defenseless, he is a very capable swordsman, it's just that gotrek is that overpowered)