Kaku Xu backstory:
Where He Came From: Lies My Parents Told Me
Kaku isn't human. He's one of a monster species so rare it has no name. Members of his species absorb the parts of other creatures in an effort to become perfect.
Kaku was born in the Nevernever, and took on human form after eating his first meal: a human kidney. He would likely have grown to become just another monster, had not his parents been killed by a pair of married human monster hunters from an obscure Japanese group dedicated to the protection of mankind.
The monster hunters didn't have the heart to kill a monster that looked like a baby, and somehow they got it into their heads that they could raise him to be human. So they tried to do that, concealing all evidence of his real nature as he grew up.
What Shaped Him: I've Got You Under My Skin
The attempt to raise Kaku as a human almost worked. But when he was 15, he witnessed a car accident in which a young street racer was killed. Looking at the corpse, Kaku felt an irresistible urge to eat it. He ended up consuming the street racer's heart.
Suddenly, Kaku was an amazing driver and mechanic. The sudden rush of competence and power that came from eating someone's heart was an important formative experience for him.
His First Adventure: Are You Now Or Have You Ever Been
Kaku ended up looking for another person to eat part of. He got his chance when an assassin tried to kill his father and got a sword to the face for his trouble. Kaku snuck out to the assassin's grave, dug him up, and ate the eyes.
Unfortunately, Kaku's adoptive parents noticed. They alerted the organization they belonged to, which decided that he had reverted to the ways of his species and that he should be killed. But his parents couldn't bear to see him die, so they told him everything before smuggling him out of the country.
This left Kaku with some severe identity issues and a belief that he was a monster. It also left him with no family after the organization killed his parents for their "treason", and a set of highly capable killers looking for him.
Who He Crossed The Path Of: The House Always Wins
Guided by a belief that he was an irredeemable monster, Kaku decided to embrace his nature. He began hunting people he considered to be truly skilled in some way, including a musical prodigy, some Olympic athletes, the CEO of a major corporation, and a Nobel-prizewinning chemist.
In this way, Kaku became superhuman. He now possesses a varied set of competencies greater than that of any human alive.
He's grown fond of challenging people to contests of skill, and beating them effortlessly. It's childish, but so is he.
A long record of doing this has given Kaku a rep. His current false identity, Hubert House, is well known for "always winning".
This reputation will probably lead assassins to his door, but he hasn't quite twigged to the fact that he's being hunted by his old gang.
Gawain De Fosse backstory:
Where He Came From: Lies My Parents Told Me
Gawain was raised in what is best described as a brothel for fey. Like all the children there, he was a changeling. And like all the children there, he had a strange childhood filled with bizarre pranks and misinformation. This gave him some very strange ideas about the world.
For example, it made him think that his name was normal.
What Shaped Him: I've Got You Under My Skin
Gawain grew up to be a good changeling, clever and deceitful. Among the children of the fey brothel, he was something of a leader. Which meant that when he was 16, he was the one chosen to represent them at a meeting with Queen Titania.
He fell in love at first sight with her. To proclaim this fact to the world, he got a huge tattoo on his back with her name and picture. But his attempts to romance her went nowhere. Eventually he worked out that the only way he was going to get her was to become the Summer Knight. And for that, he'd need to be someone who mattered.
His First Adventure: Are You Now Or Have You Ever Been
So Gawain went to Vegas to seek his fortune. He made a lot of money cheating at poker with his Glamours. Eventually, he made enough money to buy a share in a casino for himself.
When he did this, he finally Chose mortality. As he Chose, he said "I am not a faerie and I never was one either".
Though he tried to present it as an expression of his own character, his Choice was probably just an effort to qualify himself for the job of Summer Knight.
Who He Crossed The Path Of: The House Always Wins
Things went well for Gawain once he got part of a casino. He made more and more money, until he was able to buy out the other shareholders and and assume sole control. He became part of the local high society, hanging out with celebs and hosting extravagant parties. This is all part of an attempt to attract Titania's attention; one that hasn't really come close to success yet.
Unfortunately, Gawain isn't very able to pursue Summer Knight-dom much further right now. This is because the other children from the fey brothel, seeing his success, have started mooching off of him and expecting him to solve all of their problems. He feels obligated to help them.
So, Haru, what do you think? Different enough from one another?
PS: Just saw the note in the request saying that both should be Submerged. Oops. Hope it doesn't bother you.