But Lord Raith can't feed, right? By Maggie's curse?

Correct, Raith can't feed himself.   What Lara did with Thomas on the boat ride was Lara giving Thomas some of her energy.  Another WC vamp might be able to do that for Lord Raith.  (Which at the time seemed like the most important reason to introduce it.  It provides a way for Lord Raith to become active again and seems pretty important for Harry to consider.)

Actually I was thinking of something else.  PT showed that WC vamps can recharge other WC vamps by giving energy. It may not be the preferred way to feed, but it seems like a good way to bring Papa Raith back into the mix at nearly full power. 

All it will take is someone with access to Papa Raith to cut a deal "feed me and I'll reward you."   After that his first agenda item will either be will be killing off Harry and Thomas <or> taking back control from Lara.  Either will put him on a short path to Harry.

There's also a fair chance we'll see him in Mirror Mirror if Harry is looking for an alt-Thomas or alt-Lara.

Trying to be Eb in line has some serious issues I doubt the senior council has considered or even knows.  First off, Eb may side with Harry rather than just refuse to kill him.  They already know he has some fondness and had protected him even if they don't know the full relationship.  Second, Harry just got the best of Eb.  The recent bout should show that Harry isn't just winning by luck.  Worse, since he knows that Harry was just creating a diversion, Eb can't even be certain that Harry showcased what he can do if he really wants to throw down.  Last, asking Eb to kill his apprentice sound bad. Leveling a death sentence against a senior council member for not wanting to kill sound even worse.  While Eb being the blackstaff may be a poorly kept secret it's not general knowlege.  Just how would the Merlin sell this to the general assembly without it sounding like "yea, we kill anyone that votes against us."

True.  I could also see Harry's perception of her changing because she's just flat-out not as scary as she once was.  He was a human who was susceptible to her power before.  Now, with the mantle and the threat of Mab's offense, Lara just isn't going to risk whammying him, so he's unconsciously letting his guard down around her.

Based on PT, it sounds like Lara might not be able to consciously resist feeding if they get intimate.  I'm thinking this is a ploy by Mab to get Harry to do something else by throwing this obstacle in the way.

Here's a crazy theory.... Eb is responsible for Thomas attacking.  He decided it was time to get this whamp out of Harry's life.  This helps explain why Eb was checking up at Justine's and later freaked out and tried to kill Thomas at the Waterbeetle.   It's not rational, but it somewhat fits why Eb was so personally invested.

No, Harry mentions the idea -- "getting Faustian" -- and Murphy shuts that down "firmly."

That discussion is what made me think of it... Also, wasn't Summer described as the force that polices Winter?  Murphy has always put what needs to be done ahead of Harry (and other past relationships).  She makes a pretty good safeguard against Harry in a few ways.  Harry couldn't bring himself to use his might against her, but she doesn't have the same hangups (or priorities).

No, he never mentions giving it to her. I don't think it came from Justin either.   My guess is that they do get passed down through family lines and may even stretch back to a group that originally had them created for a reason.

I was just listening to Turn Coat and Lara Raith had a rather interesting choker with a blood red ruby in it. Perhaps similar to the one Harry got in Changes? I don't recall her wearing that before, so it seems to be part of her combat attire.