Dipper Pines: LII
Mabel Pines: SEI (maybe IEE)
Stan Pines: SLE/ILE
Wendy Corduroy: ILE
Pacifica Northwest: EIE
In regards to Mabel and Dipper's sibling relationship:
Alex Hirsch: Well, the first thing is to start with my sister. When I came up with the show and pitched it to Disney, the thing that I was most excited about — sort of tied in excitement with being able to tell stories with magic, monsters and mayhem — was to make fun of my sister for twenty stories a year. I was really excited to mine my comedic relationship with my sister, to deliver her weirdness to America, and that’s probably the core of the series.
When me and my sister were growing up, we just had very different personalities. I was sort of analytical and took myself too seriously, and she was sort of goofy and nuts and full of love — too much love, she had a crush on a different guy every week. And of course I would just be off in the corner, silently judging and saying “I don’t know about these guys.” One of the joys of the show has been taking my memory of growing up with my sister and fusing them with some kind of magic weirdness. The relationship between the twins is very much based on my relationship with my twin sister.