It comes to a surprise to the sisters when people still send marriage proposals to Elsa.
(well, not a surprise to Anna who always felt her sister was the better, prettier, mostest wonderful part of the family and those who didn't realize that needed glasses. Whenever she brings it up, Elsa whirls her train with an icy flat look and there's black ice everywhere)
Elsa surveys them critically and spends hours into the night, drafting polite replies that usually end with a nuanced version of "you're not my type ps I'm married to my kingdom."
Sometimes they send portraits and those Elsa keeps. They curl up around the warm fire, giggling over the pastel-brushed nose hairs and the delightfully smoothed mustaches the princes are pretending not to have. Sometimes, Anna feels kind of bad for these unknown suitors.
But then she remembers Hans and cheerfully helps Elsa toss them into the fire with vindictive glee.
Deep down, Anna knows the truth of her sister's lack of intent towards marriage. Elsa let Kristoff in, even if at times Elsa squints at him for long hours at the day, as if he was a puzzle she had yet to decipher.
(or one of those math problems Elsa loves to finish but hates to be stuck in the middle of. Anna doesn't bother trying)
Anna loves Kristoff for loving her and she is selfish in that but what's wrong in being loved? But Elsa loves Anna like glass, like the forever ice she brings. It is cold and sharp but it has always existed, before Anna learns to see it for what it is. If Anna couldn't see herself in Elsa's love, she's not sure who she would be.
Elsa is warmer now. She will never be warm enough.
Not all the proposal letters are for mockery. It can draw out a timid smile and a brief laugh, but it vanishes quickly, as if she is catching herself in the act. Anna never questions it, just takes them away from her after a while. Elsa is queen and sister. Sometimes, that is too much for anyone.
(and Anna knows that she is sister first and for sisterhood, she stays.)
(and she is glad)