My thought is that for full symbiosis the coins have to be in contact with the host, if contact is broken you have the shadow until contact is resumed. As powerful as Lash was she couldn’t heal Harry, whereas Lasciel could have. Once the host dies so does the shadow.
Shooting the coins out would work, the host would die along with the shadow, as it is unable to heal the host.
Going hive mind works as Tessa did, one of he subunits would be in physical contact with her coin, and the rest would have the shadow of her Denarian, it’s how she is able to control them, the shadow is doing it.
Marcone doesn’t have his Denarius implanted, he has it on a chain around his neck so he exposed this as a potential weakness to Harry without probably knowing it, Namshiel would have known to tell Marcone this, so Namshiel is holding things back. Alternatively Marcone does know but wants to be separate from Namshiel part of the time on his terms, (he wasn’t wearing the coin during the infamous locker room scene) to keep control over Namshiel.
Blood In His Stool would likely have had his coin implanted or ingested, so he would have survived for a considerable part of the process of being rendered into mincemeat, but at some point the coin would have separated from his conscious flesh killing him. Unless Sasquatch have a decentralised consciousness, like Tessa uses, at this point Blood would have died in Hades domain with Hades control over his ghost. The only things that Blood had to trade were the coin, and information. Hades physically had the coin, so Blood could only have traded information what was Nicky up to, his true target and long-term plans. Hades is a powerful god in in his own desmesne, he could have traded the release of Blood’s ghost. It is Blood’s ghost, making itself an ectoplasm body which has been seen. A Sasquatch Ghost must be immensely more powerful than a human ghost more in line with a spirit like Bob. I wonder if this is where the Wendigo myth would fit in? That Wendigo are Genowswa who have died possessing humans, shapechanging them back to their original form, adding ectoplasm to increase their bulk. If Blood knew this it is very much worth his while to bargain for his release, he has an option other souls don’t.
If so Blood would be diverting considerable power to keeping his ectoplasm body together, and would be vulnerable to the Dawn. Those are advantages Harry can exploit, especially with Mortimer’s help. However there may be an innocent mortal human inside creating a dilemma for Harry.
I think these two theories explain coherently how the coins have worked consistently in series and the Wendigo theory explains Blood being out and about. The latter makes sense and puts a new monster from myth into the Dresden canon. Bloods no longer a Genowskwa, he’s a Wendigo.
