Summer's research reveals the the threat, in The Soul Blade Chapter 25.
Brenna's morning is after being up late with Matt. Krista's call is to get the information about the death in Sacramento to Brenna. The reactions were the goal for the conversation, and after that scene, I realized that I do a lot of dialogue. Go fig. The call from Summer clarified the spells. It also has a sequel hook, though that wasn't the plan at the time. Summer wants the excitement of Brenna's life; she is well aware of the Blade and sees it as a cool thing, not the curse that her cousin sees it as. The decision to have the information sent as an email meant not forcing the reader to sit through an infodump.
Tricia's reveal of why she chose the suburban housewife was inspired by the Terry Pratchett and Neil Gaiman novel, Good Omens. One of the characters, Crowley, is a demon who has a more modern look at spreading evil. While his fellow demons are craftsmen, with one tempting a priest and expecting to have him in a year, Crowley causes a massive traffic jam. The drivers trapped then take out their frustrations on others, who then do the same to even more people. A wave of taint spreads out, affecting a far larger number of people*. That's the line of thought Tricia is using; by killing someone is a safe suburb, and leaving the body to be discovered by her children, she's spreading fear as fast as the media can report the crime. J. Random Surferdude in San Diego doesn't bring out the media as someone killed in her own home.
The advice Missy gave Brenna about starting a blog I eventually used for myself. I started blogging in 2012. The idea of Brenna writing down the stories she hears from ghosts and publishing them on a blog is a good one. She'd have a unique voice and unique perspective about history, even if no one believed her about her sources. Missy's choice of browser was based on the one I used in 2009. Opera is a real browser, originally promoted as being small enough to fit on a 3.5" floppy disc. I gave up on it when it started having problems with .gifs, requiring me to click on the element before it even loaded. It could be fixed now, though. Hindsight tells me that the tab Missy had for slashfic probably should have been for Supernatural. However, Stargate SG-1 comes before Supernatural alphabetically, so her fondness for Wincest is still hidden from Brenna.
With the email from Summer, much like the phone call at the beginning of the chapter, the goal was to show reactions. Infodumps aren't the best way to get details to the audience, and the, "As you know, Missy," approach will have people wondering just how pedantic Brenna is. The reaction to the infodump is the important piece. There's a difference between, "Oh, crap!" and, "Oh, this again?" Brenna's reaction is to call the police.
Friday, Brenna brings Detective McCoy up to speed, in The Soul Blade Chapter 26.
Also Friday, over at Psycho Drive-In, "Rinse the Blood Off My Toga", for a belated Ides of March celebration.
Saturday, over at The Seventh Sanctum, Nancy Drew.
* However, as goes evil, so does good. Crowley accidentally caused a telemarketing call centre to be eaten by an angry Hastur. The calm from the telemarketers not calling people and interrupting lives meant a wave of good feelings spread out, undoing the work from the traffic jam.