Desio988 wrote this on vampirediaries.net and i think they makes some good points.
Stefans not copying Damon. Paul isn't copying Ian. They are both amazing actors with different approaches/styles to different characters.

Sidenote: Does anyone remember the episode in season 2. Where STEFAN had the room
full of girls to feed on? That was Stefan's thing, not Damons.

k, everything I'm bout to say, has a perameter. The parameter is....when they are evil. So only concentrate on when they are evil. Not when they are good.

They have two different approaches to this "being bad" thing. Here's the reason why.
1) Damon's evil is a byproduct of his pain, because he's been hurt.
2) Stefan's evil is a byproduct of an addiction. Not only too blood, but to turning himself off.

Damon turns himself off, cuz it's easier to deal.
Stefan turns himself off to escape what he has to deal with.

See the diff?

When they're both on killing sprees, one is emotionally driven, and one is not. Paul and Ian display this perfectly and distinctly.

When Paul is atuação out Ripper Stefan, he looks psychotic in the eyes...like a sociopath with an addiction. Or like Golem of LOTR. Paul's style of bad Stefan very much reminds me of the Joker. The Joker with a debonair suave quality. Joker is an emotionally dead killer.
We got a glimpse of that "Why so serious?" Stefan at the end of last weeks episode.

Ian always tells Damons underlying unstable emotions with his eyes. He projects Damons emotions on other people with those bad boys, while his words say other wise. Which is why no one ever believes him when Damon says "I'm fine. I'm not going to do anything stupid." Ians style of bad Damon is like an ass. When hurt, and backed into a corner...he lashes out. It's all emotional self preservation.

Now between the two. Which one do you think a majority people would identify with. How many assholes have you met? How many Jokers have you met? lol. How many of you have been hurt? How many of you have an addiction? that's my point.

I think the problem is that people don't understand Stefans evil. In comparisons to Damons it's a completely different unrelatable evil. We can relate with an asshole, but not with a Joker. We can relate to a jerk, but not to a junkie. So it seems like he's copying when he's not. Because in our minds, there's only 1 type of evil...evil with a cause and emotion attached. Stefan is something else entirely.

Elena "Sounds like you were Damon"
Stefan "I was...much worse."

Those who do the most good, have the potential to do the most evil.

Anyhoo, those are my two cents. I ship Stefan and Happiness lol. Whether happiness is with elena or not. I ship Stefan/Happiness. But both Paul and Ian act their butts off to finest quality. I amor it. It's because of their atuação that I can spell out things like this. I amor it.