If you don't like Meg fine. But there is ONE argument that makes me want to slam my head against a desk until my face is a bloody pulp.
Essentially, the argument is made bits and pieces of:
"Meg's a villain, and she should stay that way"
"But Meg's a demon. Demons can never change."
"Look at all the horrible things she did in season one!"
"She killed Ellen and Jo!"
Okay. Okay. First of all, I'm pretty sure that at least half of the posters who make the Ellen and Jo statement didn't even CARE about them until recently. Not saying all of them, but I'll place my money on about half.
Secondly, guess what guys? MEG HAS CHANGED. No, I don't mean in the "Megstiel feels" sorta way. I'm not even commenting on the last episode.
I'm talking about every single appearance she has made since season 1. Meg is many things, but a stagnant character is not one of them. See she's gone through this little thing I call character development. You know, where a character changes and grows from where they were when we first met them?
Is Sam the same Sam from season one?
Is Dean the same Dean from season one?
No, and HECK NO. These characters aren't being "OOC" or whatever. They are continually changing. A good reason why I like this show is that the characters actually develop and change as time goes on. Think about it: would have season 5 worked with a season 2 Dean? No. The characters are evolving and going through what we go through (in a less apocalyptical manner) each day. We aren't the same person we were a couple years ago. As Meg said: we learn. We grow.
Meg is no exception to this rule. In fact she may very well be one of the most interesting characters in this show because she has shifted from black and white to shades of grey. This is not a bad thing. In fact, I'd say it a good thing.
Here's why: Meg is the demonic parallel of the boys, argumentatively, specifically Dean and Cas. Meg served her father in Season 1. So did Dean. Meg began to question her father in season 2. So did Dean. Season 5 rolls around, and she is serving her God. Here, we can link her to Castiel. UST aside, the dynamic of that scene was in the parallels…Meg is serving Lucifer, but begins to doubt. Reflecting Cas' serving of heaven, their devotion and doubt are very similar. Then comes season 6. I like to say that here Meg is in the same position as Cas is in that they are both rebelling against their ruler and fighting for control. Also, note that while she has maintained her wit and snarky attitude, she is far less full confident than she was all those seasons ago. She's fighting a losing battle. Just like Cas. Just like Sam and Dean.
Which brings me to season 7…honestly, the sheer difference in Meg's portrayal caught me off guard at first, but now I get it: Meg's tired. She'd weary. She wants it to be done. Compare and contrast to Sam an Dean, and their weariness as well. And then, with this last episode, I can confidently say she is mirroring Cas in a rather beautiful way: she has become less sarcastic and a lot more serious. He has become less serious and more distracted. She and Cas are both echoes of who they once were because they are so TIRED. They have fallen so much from where they once where…she used to be, essentially, the king's daughter. He used to be the leader of an angelic army. She used to serve her God by his side. He used to serve the Heavenly Host. They have both lost pretty much everything.
Meg's a survivor now, and has descended into morally grey territory. Actually, I'm wondering right now whether Castiel is the only chatacter who will go down the path of redemption. It would be interesting if this happened to Meg as well; she's evolved so much since her first appearance, so for her to regain her humanity would be both a good twist and an amazing character study. I would like to see it being attempted.
In conclusion, yes, Meg is different. This is not being out of character. This is developing as a person. So to say that she can't change because she's a demon/villain would be a rather superficial statement. Characters, or at least, the interesting ones, continually change as time goes on. To say Meg cannot change would be an invalid statement in of itself because she has done nothing BUT change since her first appearance.
And yes, Meg was a cold blooded killer who killed many people, including Ellen and Jo (RIP). But so has Castiel. And Sam. And Dean. And Gabriel. And pretty much the majority of all characters ever introduced. To single Meg out for that and use it as a reason for her not being able to change would be rather…stupid.
Reasoning that Meg cannot change because of her species or because of her villain status would be ignoring the seasons of change that she has already gone through.