Send me an AU and I’ll write 5 headcanons of it
Merida died in a terrible accident many centuries before Jack. It happened during an outsider attack, it was a surprise battle and the Highlanders werent ready. They sent Merida and her brothers away in Angus to the forest for safety. Some soldiers noticed though and followed them. They arrived at a sacred stone pillar circle, there they were ambushed. There were 3 soldiers but Merida was still outnumbered. She combated the soldiers, took 2 down with her arrows and the last one was getting to her; she sent Angus away just in time to turn around and stab the last soldier with her last arrow but not before she was stabbed as well. The Moon was her witness, her sacrifice known and so she was revived. Merida was untrusted to protect the family and siblings with her spiritual powered arrows and animal guides (bear, clydesdale and eagle) and to be forever burdened of her death and what she had to see pass in time without her. Merida has remorse over Manny for reviving her instead of leaving her to die in peace and wait her family in the gates of heaven at her own time, now she will never see them again. Merida stayed in Scotland for many decades until she felt it was time to see the world.
Merida was still a minor spirit yet known through many cultures as the protector of the home and brotherhood/sisterhood. Merida got to see Jackson grow and take care of his little sister through her guidance, she wasnt there to witness his death so she never knew what happened to him. She feels guilty of the siblings she took her eyes off for a week and wasnt there to protect them and so left the little village to take her job more seriously.
Merida has fun with her powers, she guides those lost with her wisps and can make people feel wonder and hope with her animal guides (she can either request of them or transform into them); scaring off burglars and stalkers. She likes playing ghost if you havent noticed.
Jack and Merida meet post!RotG while she was checking on the Bennetts, she was very surprised to see another spirit, a believed one at that with her charges. She gets angry at Jack for putting Jamie in danger (sleigh tricks and stuff) [”Why do you get so upset about?! We were having fun and he is MY charge as well, remember sweets? I will never let anything happened to Jamie or Sofie ever”] [”You dont understand Frost, it is my job to protect siblings and I cant do that and concentrate in millions more while I know youre putting THESE particular set through dangerous adventures! I won’t allow another older brother be lost to a sister under my watch again! EVER AGAIN! I WONT LET SIBLINGS GET SEPARATED AGAIN!]
It is muchmuch later that Merida realizes this is Jackson Overland, the boy she lost to the winter all those centuries ago. She apologizes immensely, for his death and for leaving his sister behind in her sorrow. Jack then sees how depressed Merida really is, how her job is more a burden than a blessing like his power of fun is and so he makes it his mission to lighten her up.