Since Elsa appeared in season 3 finale of Once Upon A Time, alot of fans wanted to see Jack Frost from Rise of Guardians and Elsa meet together as love interests. I thought it would be a perfect oppurtunity to put Jack Frost in OUAT and alot of fans would agree. Jack you may be from Dreamworks however you were also a Disney character in the Santa Claus franchise.
1. Since Elsa and Jack Frost are centuries appart sadly, This will be the perfect oppurtunity have Jack Frost's story and/or timeline can be started from scratched and doesn't have to be based of the ROTG timeline.  Making Jack being in the same timeline as Elsa would make perfect sense.
2. There has been so many fanfictions and story plot ideas around Jack Frost and Elsa even within the Frozen movie that are very legit. Using these franfictions/story plots in OUAT would bring a whole new level of viewers and ratings to the show.
3. Jack Frost can change Elsa's character development by teaching her how to control her powers without having to worry of hurting anyone and learning to upon up while being able to upon up. Not only this will bring Jack and Elsa closer together but it also builds a great love connection between the 2 characters.
4. Imagine how Jack Frost would interact with main characters in OUAT. His sarcasm,humor and fun personality would actually make Captain Hook suspicous about Jack.
5. If Jack Frost would be part of OUAT there is a good chance that his main villian Pitch Black would be very dangerous to the OUAT unviverse. Pitch would be the perfect villian to make Elsa evil out of fear and join the Evil queen. Oh GOD!!
6. Jack Frost could be the main reason why either Elsa got her powers before she was born or how Elsa got put in Rumplestillskin's jar.
7. Having Jack Frost and Elsa on OUAT would bring in tons of moral lessons to the show that are 100% relateable to anyone. Example: Don't let Fear nor anger cloud your judgement and even though you have a rough life in the past there will always be hope for you in the future.
8. Jack and Elsa have a Romeo and Juliet element to them but with new whole new heights
9. Someone who really cares for Jack Frost and Elsa to meet as a couple as much as thousands and possibly ten thousands of fans.

     Throughout Youtube, Facebook, Twitter, Instagram, Tumblr and other social media websites; are Jelsa fans wanting a crossover between Elsa the Snow Queen and Jack Frost the Winter Spirit as a couple. It has become massively popular, that fans has also created their own merchandise and cosplays. Such as during this year's event of Salt Lake Comic Con, where one couple created their own Jack Frost and Elsa cosplay in steampunk version. It is not only in the United States where this ship is beloved, but worldwide such as Japan, Portugal, Hungary, South America, Canada, Denmark, Greece, Italy, United Kingdom, and more supporters not listed here.

 On top of that, think of the profit when two unforgettable fantasy characters can be seen as a couple (such as Snow White and Charming), not only seen as supporting characters. 

 The purpose of this petition is to not only gain supporters, but to also give a shout out to help spread the word to other petitions who ship this couple.

Sources:

 1).Salt Lake Comic Con: http://fox13now.com/2014/09/06/crowds-of-cosplayers-make-salt-lake-comic-con-most-attended-convention-in-utah/

 2). http://www.change.org/p/dreamworks-jack-frost-from-rise-of-the-guardians-and-elsa-from-frozen-should-be-in-a-movie-together-as-love-interests

 3). http://www.kdramastars.com/articles/35918/20140905/frozen-2-jack-frost-two-sequels-confirmed-will-the-rise-of-the-guardians-be-elsa-love-interest.htm

 4). http://www.bustle.com/articles/31814-once-upon-a-times-frozen-spinoff-needs-to-happen-for-these-7-important-reasons

5) http://www.kdramastars.com/articles/37294/20140913/frozen-2-jack-frost-make-it-happen-by-signing-online-petition-rise-of-the-guardians-star.htm