Destiny's Mistake (Jearmin)
When Jean Kirstein finally manages to muster up all the courage he has stowed away and ask out the girl of his dreams, Destiny comes in and completely, well... Fucks it up.
Instead of his undying and unconditional love falling into the arms of Mikasa, it accidentally slips into the hands of Armin. Suspicious from the start, Armin is taken aback from the gift, until Jean assures the gift was specifically meant for him.
WARNING: SPOILERS IN COMMENTS AND STORY