Getting to the surface yes, Lydia probably not, people on the move are hard to find because where they move next is dictated by their free will.
She did have a destination in mind when she came down here.
Thats what I was hoping to intersect on our way out.
Get all the civilians out of the way.
I wonder if she kept any of the Cindy's hair; she'd be trivial to track with a hair sample, if you believe Dresden.
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I have basic pattern recognition skills, so I can predict that if we leave without Lydia, she's going to fall into Kattrin's hands.
And there's a good chance that if they have the Ankou's daughter, they might not even need Mathews any longer to work whatever mojo they want, because direct blood connections are potent.
If we stick around to fight then this would be an excellent time to give Kat a surprise dynamic entry into the tattoo parlor. The passenger is dead, so we just have to worry about making sure the cyber devil doesn't run anyone over when it slams into the building at 90 mph with the safety features disabled.
It also might mess with her control of the zombie. DF necromancy, and in particular her tradition of it through kemmler, uses a drum beat of some kind as a sympathetic association with a heartbeat to control their minions. Stop the drum, and you kill their control.
At which point the zombie either stops doing anything or goes feral. Ideally it'd go feral while she's trapped in the wreck with it, but I'll take inaction too.
We can pop up and stab her in the back while she crawls from the wreck instead of trying to win a straight sword fight.
Tattoo parlor is the site of EMS and police investigations. Do that and you will kill a ton of law enforcement.
And sacrifice our only tracker, with no guarantee of actually killing or trapping her.
Also, its still mid-afternoon up top. In the middle of Chicago. Collateral damage YES. Witnesses YES.
As for whatever she brought with her, we dont know what it is.
Standard zombies require a drumbeat for control. I would not swear that whatever a Norse necromancer brings to play will have the same limitations; she knows that whatever could unpick her ward has to have some magic skill.