My thinking is that it was before, Grave Peril while she was held captive by Bianca.  Then like a encysted parasite or an anthrax spore,it slept in her brain, first metagating her mental health symptoms that were attributed to controlled feeding by Thomas. Nothing was noticed because it as so gradual, until it was in the perfect position to not only undermine the White Court, but the whole of the Accords.

And some people just unscrew the box and replace the hard drive.

In keeping with the computer analogy, Starborn would be a combination of fire wall+antivirus then?
... This actually makes me think of Nemesis as something like the agents from the matrix, it can jump in and out of any hardware connected to it's primary system... Or would that be more like agent smith, who over writes the program already there with its own?

This makes sense to me and clarifies some things. The last one though leans towards your second observation - since HWWBs has had an active role in the background for much longer. So it being locked up in Lea was more like Mab didn't want her second infected and was 'burning' the infection out. And HWWBs didn't like being quarantined (as you say), but slipped out and got Maeve.

Ok, that actually helps (I knew about ports and firewalls but I did not get your analogy). So, what would be the relevance of free will?

• The Outer Gates are a Firewall that block almost all traffic from the Outside.
• Free Will Summoning is a Firewall Port that's open to the Outside that allows traffic in.
• Black Magic Use is something that opens local Ports on the user, which Outsiders can use to access the system.
• HWWBeside is a Hacker who's gotten inside the firewall and can use Black Magic Ports to open more Ports on local systems, including Remote Access Protocol.
• The Athame is a USB drive with HWWBeside's malware that will open Ports without Black Magic Use initiating the intrusion.
• HWWBeside is likely hosted on a system inside the Network (Reality), which is his foothold.
• HWWBeside might be able to pass from host to host if the right ports are open.
• The question is if HWWBeside is limited to one system at a time, or if he can be on several.
• The possession of Lea shown in PG implies that HWWBeside was trapped inside Lea at the time, but managed to escape her system and moved to another.
• This could mean HWWBeside is limited to actively possessing only one host at a time, but it may be that he can be on several (my guess would be three) and he didn't like having one of his install instances/licenses tied up on a quarantined system.

She gives him a suit and a ring.

More "flowy", yes. I think I've seen a comic book woman wearing something like that, covering even her face, but I can't remember where.

The White Court is Etruscan in origin, it is the language they choose to converse in. The Etruscan’s had their own version of the Fates,  same beings different names to the Greek.

What if the cloth was a gift from the Fates? A Ravelling as opposed to an unravelling. Given that The Queens of Faerie are inheritors of the Greek Fates (amongst others) it may explain what Winter wants with an alliance with the White Court, they are revisiting an old association. Oh and the God of War in the Etruscan Pantheon, the Ares equivalent is  Laran.

I think that the White Court arise out of something that happened in relation to Erus (Eros) and Psyche,  the original Whamp being a scion of them or their daughter Volupta/Hedone corrupted somehow. Psyche is depicted with butterfly wings (Psyche is Greek for butterfly) it’s no accident that is how we see Thomas depicted in Grave Peril.

What is really creepy about them is they are described as "shrouds."  This is usually what is wrapped around the dead..