To clear things up if you have any questions!

And oh, Heechul has become a "spirit" of nature, inspired by the Hans Anderson version of "My little mermaid".

The angel is Siwon. 

Their father is chasing after them because Heechul has an object called the "rainstone". It controls the natural state of the earth's land and atmosphere.

Heerin didn't want to be with Donghae because she was scared her father would harm Donghae.

Should I make a sequel? 

If so, look below!