Tear Jerker / When In Doubt, Blame the Eldar

• When Black finds Thomas: The poor kid just had his entire world destroyed by a mob of fanatics, and is desperately trying to wake up his mother, who Black can tell is already dead. It's absolutely heartbreaking, and a big part of the reason Black tries to make the Sisters of Battle suffer, seeing how they caused it.
• On the flipside, the Sisters' reaction to Black defeating Saint Anais. Even if what they were responsible for was incredibly cruel, it's hard not to pity them when they see their last hope for victory destroyed, and come to the realization that, ultimately, they were not in the right this time, and the Emperor did not approve of their actions.
• All of this pales, however, to what happens to Taldeer in Chapter 30: During the scream, a daemon of Slaanesh possesses her and warps her body in an effort to seduce Black. While it fails and is ultimately exorcised by Black, Taldeer is broken from the physical, emotional, and spiritual violation she suffered, and to make matters worse, the changes to her body are permanent.
  • Black explicitly compares the look on her face after this incident to Thomas's when his family was killed by that mob.
• Also, Thomas's reaction to Ozman going into a coma: the poor kid can barely talk, and can only wonder why the universe is so cruel to him.
  • Even worse is when Gebbit tries to comfort him by saying that the Emperor will protect Ozman's soul, as it's heavily impiled that the Big E is the reason Ozman is in a coma in the first place.
• Selena Agna's reaction to the Scream: it costs her all of her Sororitas, pretty much shatters her faith and mind, and ultimately leaves her a crying wreck. While she may have done some incredibly evil crap in the name of the Emperor, here, you just want to give her a hug.
• Hell, Black's reaction to the events of Chapter 30 and everything afterwards. He's forced to come to terms with the fact that the universe he is in isn't just messed up, it's dying, and there is NOTHING he can do to save it.