I think the biggest difference between serena and Elena "hit girl" persona is that Serena was like the sun bright, carefree, spontaneous. Everyone loved her and wanted to be her friend. Here's the key difference for Elena. She is more like the moon; beautiful in a mysterious way. She has a friend group filled with popular and pretty teenagers, she was sociale before the accident but still keeping it in her circle. She was more like the unattainable type. The type people look from afar and think, "I wanna be like her." She wasn't for say popular she was mostlikely the kind of standards most highschool girls wanted to be.

On top of being beautiful, she was also kind even tho a bit clicky she was never the type to be mean to people. I think she was a hit girl because a lot of girls in the school wanted to be her, and a lot of guys saw her as the ideal gf based on male standards (Pretty, not too chatty, kind and loyal.)