Ascalon is a genuinely good character though, I like her interactions with Manfred and Theresis and the extent that one of Arknights' main themes, finding yourself and your own identity, is emphasized in Ascalon, more so than in the other characters.
Where Kal'tsit, Theresa, and Theresis already know themselves, and the Doctor suffers from the consequences of allowing themself to be smothered under the weight of their guilt, Ascalon is at the crossroads in Babel of needing to find her own sense of being.
This is the point that Theresis makes to her more than once. It is not necessarily that siding with Theresa makes him mad, but it is more that she is merely copying Theresa's convictions and not finding her own reason to live and fight against the world. What happens when that goal succeeds, or when the worst happens?
Well, we see what happens in Ascalon's file. She goes on a revenge killing spree, killing as many people who know her as possible, and being gone for so long that there are genuine concerns about her mental well-being. She's trapped in a maelstrom of the past, unable to let Theresa go. I think this sentence by Kal'tsit is important:
I hope that this work can help her find a goal, faith in something, or perhaps even... a measure of regularity in her life.
Whether or not she has found that yet is not clear in the story, but from what I know, Ascalon doesn't appear in side events or any story past Part 2, so here is hoping that Ascalon can find herself in the shadows and the mist.