Universe 1 Alternative Time Line

Well who tf they are?
Elina: She is a half legendary Saiyan From universe 1 pretty competitive and tomboy who tries too hard to be tough but pretty insecure on the inside who really cares about her loved ones even if she doesn't show it , Her Father was a saiyan with Legendary blood (like our boi broly) and her mother was a normal saiyan, wich makes her weaker but more stable than a normal berserker saiyan (legendary or whatever shit you want to call it)
Kai: He is a kaioshin born talented figther, a figthing maniac with a lot of experience and training.
Cringy short version of the story: She lived with them until she was 10, when her Father lost control of his power causing him go in a rampage killing almost all the members of the village but her mother escaped with her and then leave her in a distant cave to wait for her while she tries to calm her father
but she waited and waited and her mother never came back, so she got tired of waiting and start seaching for her mother. Without results she found herself lost in a forest, were was found by a little group of yardrats that were on the planet looking for a relique of their race, they decided to help her out, at first she was reclutant to go with them but she end up following them
On of the scouters spotted her village finding no more than a lot of destruction and corpses, when they saw that she have lost everything they decided to lie to her and take her with them to their planet saying that her mother said to them that she have to go with them to wait for her, a big mistake...
She lived with them for 3 years, they saw her potencial so they teached her some martial arts to defend herself and mantain her busy while waiting for her mother and father, asking to her saviours if when her mother was coming... but the only answer that she got was "Soon".
Meanwhile Kai, by a coincidence, decided to look at the future of the yadrat planet using his time ring, when he saw a powerful monster killing all of the yardrats, he never interfere in the course of things, but something inside him wanted to figth agains that monster, so he decided to find it and kill it, (i got tired of writing so) that monster was Elina.
Two years later, Elina's rescuers decided to tell her the truth, making her feel overflowed with sadness and rage, making her lose control and releasing all of her locked power and go in a rampage like her father, killing and destroying all that she can see.
After two days of incontrolable power, she falls unconscious out of tiring herself. When she wakes up, she is no longer in the village, in a place that she never saw before, Kai took her and since he saw her power, and he is really looking for strong opponents, he decided to took her as his pupil, but at the end, he end up heling her to control her power to make her even more powerful and calm... (yeah i got tired there is a lot more but is just a description)

Sumary, She is training with kai to control her power, now she is 27 years old, Kai is strong as ever, and similar stuff
If y'all want to know how tf did she learn all of that stuff, how tf did she got possesed? then let me know and i'll wrote my shit here since i am too lazy to wrote all of my notes for no reason