You can call it pulling the trigger on her emotionally, or you can say he showed her the truth.  When she realized that Martin was pulling the double cross and her little girl was going to die because of it, it pissed her off and she proceeded to rip his throat out as most loving mothers would. 

Then Harry explains to her as she is turning why the Red King wanted to kill Maggie, further explained that as the youngest vamp, she could kill all of them with her death.  Susan is conflicted some as she is turning, then she looks at her daughter, she tells Harry she doesn't think she can do it.

Then she says to Harry; page 419 Changes
At that point, there was only one way to save little Maggie, they both knew it... Yes, she was telling him to cut her throat, it was the only way.

"One day I hope God will forgive me for giving birth to the idea that came next.  Because I never will.  I knew how angry she was.  I knew how afraid she was.  Her child was about to die only inches beyond her reach, and what I did to her was as good as murder".....

Sounds like he made a deliberate decision here.  Hey could have thought of something else, but he chose this.

Harry is a member of Winter.  A Way to the Island may take him through territory that he's not welcome.

I'm wondering how she will respond to Harry marrying Lara. 

Interesting.  I wonder if it's more like Nicodemus loses the Noose in a fight with Harry.  Harry turns to see Marcone put it on.

My money's on Carlos he's due for a power up, White Council loyalist, Warden officer (Just like Eb used to be). If nothing else Ebenezar would figure Harry has enough responsibility, plus you know he's no longer a member of the White Council. I doubt they'd let the one guy who can break the laws be Harry.

Eb was the Captain of the Wardens.  Not sure but I think that means he was the leader of them behind The Merlin?

Like I said, the Blackstaff chooses the wielder.  I really don't know if it's the Staff or if it's the person wielding it that decides.  Anyways who do you see getting it?  Besides Dresden, Luccio, and Carlos I can't think of likely candidates.  If you come up with other names, I will add them to the poll.

Sure it does.- Harry points it out to Morgan all the way back at the start of the series when he tries to harass Harry for binding Toot-toot.

The Seven laws only apply to humans, not Faeries, or Gods, or Vampires, or anything else.

Exactly.  Also he didn't bind Molly the way the Council set the laws.  They are talking about when you use someone's Name, or blood, or something that basically enslaves or controls a human.

My guess is that Harry didn't say he loved Susan in the basement of Bianca's mansion. She went feral, knocked him out but didn't kill him because of the poison in his blood, so she killed Justine instead.

Upon waking up, Harry got out and headed upstairs to find Susan fully turned with Bianca. He couldn't kill Susan, so he walked away rather than fighting.

I also like to think he still beat the Nightmare while unconscious, and ate his power. By not using it to destroy the mansion, is stayed within him, partially corrupting him.

I also think Bianca could have sent footage of Harry's attack at the party to the White Council, which declared him a full warlock. Since the place wasn't completely destroyed like it was in GP, security footage might have survived.

Thus Harry starts on the dark path with isolation and regret while being hunted by everyone.

Oh that's a great theory.  I don't think he beat the nightmare.  He's lost his love, and his power.  Bianca wants him to live a long life like this, and lets him leave.  He swears to himself that he will do whatever it takes to make her pay.  He asks Bob how he can charge up his power in a hurry.  Bob refuses to tell until Harry makes it an order.  It's there that he begins tapping into Necromancy.  He must start small in his weakened state, just a single shade at a time, but consumes more, and more.  Not only does he gain all his power back, he surpasses it. 

As for his standing with the White Council.  I don't know if he will be declared a warlock.  I think he gets kicked out for violating the Accords.  It's later on that they discover he's using necromancy that they go after him, or maybe he nukes Bianca's place to get revenge resulting in many casualties, including mortal security.  White Council finds out, deems him a warlock.

I also wonder if Harry will be straight up evil, or will he be more like the Harry we wished he would be sometimes (smarter, doesn't hold back against enemies).  Maybe he see's killing other Harry's as not murder because it's just him lol