I also like the idea of couple who grew up together.

Lately, Disney has already done the princess is the villain (Merida in Brave) or the princess is on the villain's side (Megara). We've also seen the princess and the prince or the boy and girl are merely friends ( Moana and Maui, Judy and Nick, Ralph and Vanellope). The princess has learned from the prince, before-- i.e., Mulan learned martial arts from Shang, Tiana learned to "loosen up a bit" from Naveen, etc. The brother and sister relationship would only work if the story was original or a reworking of Hansel and Gretel. We've already seen sister siblings with Frozen.

That leaves the couple who grew up together...which Disney has never done...to my knowledge, aside from the animal films ( Bambi, Robin Hood, Brother Bear, The Fox and The Hound, Lady and The Tramp, The Lion King, etc.)

All of them.

I wouldn't say merida and elsa are on the villain side

I would LOVE this.

This would be so cute

@Wavesurf and @Disnerdtobe: I don't think Merida and Elsa are in the villain side. Merida shown madness and angry at the most time, she made her mother in the dangerous, but it doesn't mean she's a villain. She just doing something wrong, and she realize it.

Elsa is more like to be misunderstand as a villain, she froze the kingdom and Anna, but she didn't mean to. I don't see her to be in villain side, unless for the uncontrolled ice power, though.

But the boy and girl relation picture is cute.

And the one with the princess learning from the guy.