Now onto Littlefinger. Moar spoilers below.

[quote=Mosis Tosis]
Disagree, I'm fairly certain he does/did have genuine feelings for Cat (and by extension, Sansa), as events near the end of SoS (and by extension, further on in season 4) will show, as does his specific history with Lysa, Cat, Hoster Tully and Brandon Stark (and to a lesser extent Ned). You're very right that he's a sociopath that is primarily concerned with the aquisition of power through backhanded dealings and treacheries, but I think he's definitely trying to have his cake and eat it too when it comes to Sansa and her potential role in the political maneuverings to come. 
[/quote]

The thing is, you never seem him actually demonstrate any genuine feelings towards Cat.

In Game of Thrones, when Cat reaches the capital, he lies to her outright and says that the blade that the assassin used was his that he lost to Tyrion, knowing that she would pursue him and try to hold him accountable for the attempted murder of her son. Her capturing Tyrion and putting him on trial is what started the rift between the Lannisters and the Starks and led to Jaime attacking Ned into the street, which kind of snowballed into the war. Littlefinger knew it was Joffery who hired the assassin, and if he genuinely cared for Cat's feelings, he likely wouldn't have ended up putting her in harm's way. The Lannisters have a reputation for being through in destroying Houses that become their enemies. You don't need to look any further than the Targaryens and the Reynes to see that. 

After the Red Wedding, Littlefinger isn't moved at all at the death of Catelyn, and it's likely he knew it was going to happen. Even before The RW, he was trying to get Sansa to consider leaving the capital with him to go to the Eyrie. After the Purple Wedding, Ser Dontos delivered Sansa to Littlefinger, and what's going to happen is he's going to make her pose as his illegitimate daughter until the time is right to reveal who she actually is. Since he knows Lysa Arryn is madly in love with him (she even poisoned Jon Arryn for Littlefinger, which as you recall, set off this entire mess), it wasn't hard to get her to agree to marry him. Almost immediately, he fakes affection for Sansa and makes sure he's caught by Lysa's bard kissing Sansa, where the bard rats him out to Lysa, who obviously demands answers and she's never been the most rational person. She threatens to throw Sansa out the Moon Door, which Littlefinger prevents happening and instead murders Lysa that way, telling her something along the lines of "I only ever loved Catelyn." Which I'm pretty sure is a bold-faced lie to be an evil shit since that horrible revelation would be the last thing she ever knew before she died, and it's also likely for Sansa's benefit. He pins the murder on the bard and Sansa remains his only witness, and this is three people Sansa's witnessed Littlefinger kill since she left the capital. She's smart enough NOT to piss him off.

So now Littlefinger is the Lord of the Vale with what is believed to be the eldest surviving Stark whom I think he likely intends to marry to give him legitimacy and claim over both the Vale and the North. This would make him one of the most powerful men in status in Westeros. Sansa's nothing more than a tool for him, a very well conditioned tool who spent years being tortured into silent submission by Joffery. It might be one of the few things that's keeping her alive.

Also, he's the one who has kept Jeyne Pool in one of his brothels, whom he turns over to the Lannisters to present to the Boltons as Arya Stark to further cement their claim to the North. Not exactly respecting the memory or blood of the woman he claimed to love. 

Tyrion said it best, he seemed to be the only person who legitimately saw Littlefinger for who he was. "The only person Littlefinger loves is Littlefinger." I can't find exactly where the quote came from, but it's pretty much exactly what he said. Damned if he wasn't right.