A exploration/expansion force from our league got captured by the deldar early on, every last kin got tortured to death or turned into horrific monstrosities except for 1 brave steeljak/combat focused iron kin whom one of their crazed flesh scientists from the haamonculi covens dared himself to "make him suffer as much as a authentic living organism" just to see if he could do it
He was put on the combat arenas and fought agaisnt countless foes from all over the dark city and fostering a increasing AM like resentment and hatred towards all non-kin kind, specially the drukhari. Every last one of his processors got heated up over the thrill of combat and processing the ways to make them pay for what they did to him and his kin. He would frequently lash out agaisnt his captord and tried to burn his own processors over 17 times
Once he got sent alongside a force of other slaves and haemonculi for a raid on a imperial mining world, where he found a way to kill off his captives and escape into the wilderness living off with the scraps from a recent waaaagh that invaded the world. Soon enough he got back in contact with his fellow kin and his league over a long series of connections that took him 50 years of exile, now he serves as the main body guard for the league's leader and is a absolute beast in melee combat, willing to go through outrageous lengths to save his kin and not be separated from them again. Also huge fucking grudge agaisnt the space elves for obvious reasons, he claims the aeldari are no different and just don't do the same horrific things out of pride in being prudes.
Half the league's exploration force being kidnapped by drukhari is a good excuse for the dwarves to fucking hate elves and smash them into a pulp with big robot hands and drills.

>Speaking of the Steeljacks, they come with two separate datasheets
six units of the big robot boys. If they are max size 6, that's 36 robots on the board. Not bad.