Cut to Dexter scouring the internet for a convention nearby that a blood-spatter expert could plausibly be invited to. Deb interrupts him, her voice trembling, saying LaGuerta pulled her off the Trinity case. You know, because she's a victim in said case. Did Deb not consider that? (The answer is no, of course Deb did not consider that.) Dexter, who is pretty much the opposite of how broken up Deb is about this, and doing a poor job of covering it, tries to bright-side things, saying this now frees Deb up to help out Miami Metro "in so many ways." Deb heroically refrains from punching her brother in the nose, instead noting, "I love ya, bro, but sometimes you're a fucking 'tard." Dex goes back to his search for a convention. He lingers on a weather convention in Tampa. Cut to...
Dexter, in LaGuerta's office, starts rambling about how better understanding the science behind meteorology could have untold benefits in his crime scene analysis, on and on, yammering enthusiastically. Finally, when he stops to take a breath, LaGuerta's like, "If I let you go, will you stop talking?" But Dexter doesn't stop talking, in fact he goes back to speedily making his case, at which point the POV switches from LaGuerta to Rita, who also waits for Dexter to run out of steam before giving Dex a confused look and a shrugged-shoulder acquiescence. Man, that couples therapy has done wonders for the shady crap Rita will once again let Dexter pull. She does barter with him, however; in exchange for taking off this weekend, Dexter can cover for her during her Tuesday night yoga classes. She also mentions that next-door neighbor (and recently single, if you recall last week's unsubtle breadcrumb-dropping) Elliott is taking the kids fishing on Saturday. Dex doesn't give much of an indication one way or the other whether this bothers him, but he's been steadily more proprietary over his family this season, so we can guess.
We see Dexter packing a bag for his trip, including his murderin' tools as well as the bludgeoning hammer Arthur gave him. Meanwhile, Arthur is also packing, which includes portioning out some of his sister's ashes into a travel vial. Kind of like you do with your contact lens solution.
The next morning, Dexter scares the crap out of Arthur as he's preparing to leave school for Tampa. He asks if he can grab a ride to Tampa and help on the build. Arthur declines and starts to drive off, but "Kyle" is increasingly desperate, talking about how he needs to get out of here, and out of here (pointing to his head). To a less murderously unhinged man, Dexter's words and demeanor here would be setting off every alarm bell you have. But with Arthur, Dexter's appeals to his charitable posturing (he references "generosity of spirit") and messianic tendencies ("you're the only one who can help me") eventually wear him down. He lets Dexter into the passenger seat and drives off.
Back at Miami Metro, LaGuerta, Angel, Quinn, and Masuka go over the Trinity case out in the open, while Deb stands at her desk not five yards away, eavesdropping and correcting them under her breath. They go over the description of Trinity as determined by the forensics and Lundy's research: close to 6'4", blue eyes, age 50-60. Angel snarks that this description will come in mighty handy among the retirees of Miami. Deb keeps miming instructions for Quinn, though he's Quinn and therefore an idiot and mistakes "DNA swab tests" for the blowjob motion. He finally gets it and proposes a targeted sweep, roadblocks where they'd collect DNA swabs from motorists. This kind of thing has worked for them in the past. The downside? Well, it'd cost a bajillion dollars, it's completely unconstitutional, and it totally fucks up Masuka's weekend (he's planning on twins!). But other than that ... LaGuerta says she'll look into the budgetary concerns (Angel flirtily offers to help her), they decide to hold the roadblocks over Thanksgiving weekend to circumvent the courts, and Masuka ... will have to suck it up. Aw.
On the ride to Tampa, Dexter is just annoying the holy shit out of Trinity, asking a billion questions. Dexter really seems to enjoy pushing Trinity's buttons -- it's been a subtle throughline in these last few episodes. Is he purposefully testing the foundation for weak spots, so to speak? Or is this more of a genuine "yappy lapdog" relationship than even Dexter would like to admit? Arthur finally tells him to shut his trap, then asks him what he's so troubled about anyway. Dexter's vague about "I did something," which annoys Arthur even more. Dex distracts by pointing out a pit stop. At the rest area, Arthur again prods "Kyle" to reveal his secret, seeming to believe helping Kyle through this is a directive from "God." Hrm. Dexter stonewalls and evades, until Arthur finally screams, "TELL ME, KYLE!" Well, now they're just making a scene. Arthur gets up to leave, which is when Dexter admits, "I killed a man." Now, lest we start to think Dexter is feeling more confessional than he should be, he makes up some cock and bull about a hunting accident. Again, as with Rita in couples' counseling, he's unburdening himself by telling the "truth," if not the actual truth. But the remorse he's feeling does seem to be genuine, and he almost gets overcome with emotion for a second. That's...jarring to see. And Arthur seems equally genuine in his empathy, which is a surprise to Dexter. Arthur stresses that confession is good for the soul and that Dexter's going to be okay.
That night, at the motel, DVO has recovered from the momentary shock and is steeling itself -- and Dexter -- for killing Arthur. He gets a call from Debra, asking about crime scene photos from the latest suicide jumper. Dexter directs her to his computer and says to have Masuka give her access. I tell you, I was certain this would lead to Debra finding that half-shredded pick of Laura Moser in Dexter's desk, or something equally incriminating. Anyway, Deb closes with this gem of an instruction to her meteorology-conference-attending bro: "If you run into that weather guy, Sonny Skies, tell him he's got a stupid name." HA! Oh Deb, you are my favorite.