In the MCU/Marvel with the Omnitrix/Ultimatrix - Chapter 14: Meeting Stark - again

Scream out.Awake and pour out the grudge left in you onto me.Then, I shall save you.

In a future timeline, the earth was visited by a species known as the Slarkovs.
Having lost their home planet and in search of a new one, earth was the next habitable planet for them.

Humans and Slarkovs made a deal with each other in return for the Slarkovs living on earth.
The Slarkovs traded their technology and knowledge for a new home.
They were similar to humans except for some of them who had slight differences so fitting into the society wasn't a problem.
Over the years Slarkovs and humans began to mate with one another and reproduce offsprings.
This in turn created a new species known as the mixed-blood.
Centuries later mixedbloods could tap into their bloodline and perform unimaginable feats.

Gustav born into an age where bloodline determines everything, struggles to fit with a useless bloodline.
His bloodline only grants him the ability to change his hair color, destroying his hopes and dreams for a great future.
His fate is turned around when an unexpected situation leads to him finding a system that grants him the power to unlock and upgrade bloodlines by completing quests but he's baffled by two quests with a five-year deadline. Success will grant him unimaginable rewards...
But only one thing awaits him if he fails... Death!

Follow Gustav on his interesting journey filled with unprecedented adventures, danger and death, maybe?

What the hell? That menace who bullied me since I was six years old, actually became a pretty girl after three years of living apart? And she even ran to our agreed duel location to confess to me, hoping that I can become her boyfriend?!

This is a plot against me! There’s definitely an enormous conspiracy behind this! I won’t be fooled by you! Even if you tear up and act all pitiful, I will still disregard you and humiliate you, until you’ve have completely paid back all my childhood grievances!

What’cha lookin’at? There are very reasonable grounds for bullying a girl!

- Description from Novelupdates

“God, please. If you are real, make my one last wish come true. Let me live.”When Callisto got diagnosed with an incurable genetic disorder at age 5, she was expected to live for only ten more years.With her life on its last leg, Callisto underwent an operation that has a one in a million chance of success called the Mutated DNA Fusion, granting her wish to live. However, the operation gave her more than what she wished for.With her black hair turned silver, cat ears overhead, and a tail from her behind, Callisto now has to live her life as a half-human and half-animal, a catgirl.