I always loved Mizi and Hyuna's reactions to Sua and Hyun Woo's death because while they understand that something terrible has just happened, they don't fully grasp the situation yet given that neither of them has ever had to face death before.
In the Arise and Walk comic, we get a direct follow-up to Hyuna's initial shock— anger. Her brother's death hasn't sunk in yet, as she doesn't know what to do when confronted with something of this magnitude, so she focuses her emotions on Luka instead since she does know how to react to him hurting Hyun Woo.
I say anger, but it also looks like a mix of disgust at Luka. "How could he do this? Hyun Woo was his friend." "Why does he look so happy?" "How could he not care about him, about my brother?"
In Wiege they seem to have retconned Mizi's reaction a bit, as she's shown to be crying before the guards even put her collar back on after Round 1. Maybe you could make a case, though, that she started crying during her transition from the stage to her holding pod since her collar is shown to be off again.
Regardless, I really like how long it takes for Mizi to process Sua's death and how she doesn't start properly grieving until MIZISUA; it really highlights her emotional underdevelopment and how sheltered she was.
After Sua's death, she's hardly there. She doesn't react at all during Round 2 except during Till's big show of killing Freddie, not able to process his song, especially not the fact that it was directed towards her. The best she's able to do is acknowledge his return.
Round 5 is the most we see out of Mizi after Round 1, with Luka being able to bring out her emotions that have been boiling under the surface for so long now.
Like Hyuna, her reaction after the initial shock is anger (ignoring that frame from Weige), funnily enough being directed at Luka again as Mizi focuses her hatred towards him, in part because of his performance, but also because he serves as a placeholder for the rage she feels towards being kept in the dark and the horrific circumstance she now realizes she's in as a pet-human.
Only is it when she's saved by the rebellion and given time to breathe does she understand what death means. Sua is gone.
