Belsa

Belsa is the femslash ship between Elsa and Belle from the Once Upon A Time and Disney fandoms.

Canon
Elsa meets Belle in Storybrooke as they looks for clues that could help Elsa find Anna. As well as how they and the others could stop Ingrid. As their search for Anna wasn't bring up any results, Belle tells Elsa that they should give up and focus more on Ingrid until Elsa explains how important Anna is to her, understanding where Elsa is coming from Belle continues to help her.

When Elsa was beginning to believe that their search for Anna was getting to be pointless, Belle encourages her to not give up and reminds Elsa that the heart beat she felt from Bo Peep's staff has conformed that Anna is alive; and that she wouldn't give up. Elsa then consults with Belle about what the Snow Queen had told her when Anna sealed her in the urn, Belle tells Elsa that it wasn't true and thinking that Belle is trying to make her feel better by saying that Elsa asks to not, but Belle assures her that she is being honest, Elsa on the other hand wasn't having it and tells Belle that because she doesn't know Anna she couldn't possibly know what might have run through Anna's head that day. Belle, however, did know Anna from when she had visit Arendelle long ago, but doesn't inform Elsa this and instead uses the things that Elsa has told her Anna and their bond to reassure Elsa that what might had caused Anna to act in that way wasn't her doing, but Elsa's stolen memories makes it hard for her to believe Belle. Before Belle leaves to take care of something, after Elsa's fading hope gets her to tells Belle that she doesn't understand and has never been to Arendelle, Belle encourages Elsa to keep looking and that they will eventually find Anna.

Fanon
Because of their brief encounters in S4 of the Once Upon A Time series and are two Disney owned and based characters that are Disney Princesses (even though Elsa is a queen who still counts as one), that have been femslash in Disney crossover ships that focuses on its princesses, there are fans who use the ship and some of its titles in both fandoms.

Since Ralph Breaks the Interest is a canon Disney crossover that has a version of the two know each other, like their once counterparts do in the Once Upon A Time series, fans of the Disney side of the ship sometimes have Belle and Elsa in the modern, style clothes that the netizen versions of them wear in the film.

On AO3, the Disney side of the ship has over 22 fanfics about it.

Fandom
FAN FICTION
 * Belle/Elsa (Disney) on FanFiction.Net
 * Belle/Elsa (Kingdom Hearts) on FanFiction.Net
 * Elsa/Lacey (Once Upon A Time) on FanFiction.Net
 * Elsa/Lacey (Once Upon A Time) on FanFiction.Net

TUMBLR

Trivia

 * In the Disney film, Ralph Breaks the Internet, Belle and Elsa appear as online versions of themselves known as "netizens", the inhabitants of the digital made world that lies within the real-life internet. Where they are two of the fourteen Disney Princesses that are from the expo-like Disney website, Oh My Disney.
 * They are two of the netizen princesses (and queen) that join in the "Neither do we!" with the rest of the motherless princesses.
 * They are two of the Disney Princess characters who serve as Princesses of Hearts in the Kingdom Hearts series.
 * Belle is one of the first original Princesses to be chosen until her completed task and role got her and a few of the other Princesses to pass their lights onto other princesses who will become the New Seven Hearts, where Elsa is one of them; beside her sister who is also believed to be one.
 * As well as Belle making her first in the very first Kingdom Hearts game and her second one in Kingdom Hearts II, while a memory version of Belle is seen in Kingdom Hearts: Chain of Memories. While Elsa makes her first official appearance in Kingdom Hearts III.
 * Are from two of the few Disney films to become Broadway shows.
 * They are two of the limit time characters in Disney Magic Kingdoms.