Did it ever occur to anyone that Ruby is acting the way that she is because it's the best way to get Sam to do what she wants? I mean, she tried one approach last year, the mean, unsympathetic, snarky one and how far did it get her? Caught in a Devil's Trap and then sent back to hell. Ruby's on a mission here. Clearly, because throughout everything the one thing that's never changed is "use your powers, Sam, no, come on, USE THEM!"

And like Sam said, she's acting exactly like Dean. Or at least she did in order to worm her way into his heart. Why? Because it's the weakest point of Sam's HUGE blind spot. His entire life, Sam's been taken care of to the point where he expects it. He expects the people around him to take his crap and then two seconds later, be back on his side because that's what Dean does. Sam's never once in his life been betrayed. People have died on him, but unlike Dean, no one's actually just turned their back for their own selfish reasons; if they have, it's been in Sam's best interest, like when Dean sold his soul or even, to some extent, every time their dad left. And when that happened, unlike Dean, Sam had a kind of surrogate parent there to take care of him. Not to mention all that stuff about 'take care of your brother, Dean', 'Sam is IMPORTANT, Dean', 'watch out for Sammy, Dean, no matter what' - Sam heard that shit, too.

I don't think that Sam and Dean are on equal footing with the self-sacrifice thing. Why? Because Dean did it stone cold sober a few hours after Sam died. It took Sam about a month and even then, he had to be drunk, meaning Sam couldn't actually make a clear, real decision at that point. And no one's saying that 's selfish, heck, that's normal. What I am saying is this; Sam's used to having everyone around him always put his best interest first, even if he's not willing to do the same and, when it comes to Dean, especially when he's not willing to do the same.

So what does Ruby do? She comes back, she's softer, she's as human as she can be, and she puts Sam first all the damn time. He curses her out, she comes back. He drinks when she says not to, she forgives him. She gives him the tools he wants even when he's being a total brat about it and comes dashing in to save his life twice while putting hers at risk. Sam, at this point, feels like he can do pretty much anything he wants to her and that he can leave her in the dust whenever because she will always come back, and to Sam, that's a sign of unselfish devotion, whether it actually is, or not. And that's actually the thing; because of Dean, that will bind Sam to you. It's why Ruby's always waiting for Sam to fight Dean for her, because the more than she trusts that he'll do it, the more likely it is he will. She submits to him because Dean submits to Sam and in submitting to him, gains everything Sam can offer.

And because it's Dean's spot Ruby's taken (or not taken, no one can do that, but replicated), the one thing that Sam will NEVER expect for her to do, is to betray him for a selfish reason. If she's evil, working for someone evil, doesn't give a shit about him at all, fine. But Sam has never had someone who actually has some affection for him choose him/herself and whatever s/he wants over him and Ruby knows that. So in pretending to have (or probably actually having) some affection for him while doing everything she's doing, she's put herself right in his blind spot.

So, no, I don't think she's come back softer or more wimpy or any crap like that. I honestly, think she's as brutal and as manipulative as ever, and this is just the best way to go about it. That's why Dean recognized it as that so quickly when Sam was telling him the story and why Dean's still wary because, say what he will, Dean knows where any power he has over Sam lies. I can't predict it necessarily but I do think that if Ruby betrays Sam, it's not going to be because of something as simple as she "goes evil" because Ruby's not like other demons, she follows because it's in her best interest to follow, not mindless because she believes in carnage or Lucifer or something. It will probably make her sad to betray him, she may not want to do it, and she will definitely still care for him to some degree when she does, and that is something that has never happened to Sam he has never been put second in someone's agenda or had someone screw him over because they're working against and not for him. The way it is.