One of my main characters is named Lucas. Lucas can turn into a cat. He struggles with controlling this power. He’s also from the bad side of town; his parents are neglectful and eventually disappear entirely, leaving Lucas to take care of his two siblings. He cracks under the pressure and attempts suicide eventually, but survives; he and his siblings go into foster care. Oh yeah, and Lucas is in a wheelchair due to cerebral palsy. He has a happy ending, but I’m wondering if I should tone it down? He’s only fifteen, so the target audience is probably upper middle grade..
I'd say you've got far too much going on in your story, with way too much stuff for a young person (heck, any person) to have to handle.
- Broken home, teenager raising younger siblings. This is a complete, very heavy story by itself.
- Teenager with cerebral palsy in a wheelchair in a bad part of town - another complete and very tough story.
- A suicide attempt is a believable event in either of the above two stories.
- Cat transformation, 'cause why not? This is a complete comic book series - with great whiskers comes great responsibility (or something.)
The description you give reads like some kind of warped "inverse Mary Sue" where the main character wins out over an unreal mountain of obstacles.
There's way too much stuff in the description. Tone it down - a lot. Pick one of the elements that you really want to express, then build your story around that.
I don't know what is too much violence or grimness for a specific publisher to publish. I expect that different publishers have different standards, and often different standards for their different publishing lines for different audiences.
I am probably not a very good judge of writing for young readers, since I was a voracious reader as a child and teen and read a lot that wasn't specifically intended for kids.
Here are some examples of children's fiction I can remember.
[added Feb. 28, 2023. In Rin Tin Tin and the Ghost Wagon Train (1958), based an television series, the protagonist, Rusty is about 10 or 12, I guess. In one scene Rusty is captured by white gun runners and some hostile Arapaho Indians. The gun runners leave rusty with the Indians, and one of them apologizes to Rusty for doing so, saying he hates to leave a white man to face what the Arapahos will do to Rusty. I thought Rusty could have pointed out that he wasn't a white man but a child. Anyway, the scene gives the impression that the Arapahos will probably do something really gruesome to Rusty. I forget how he manages to survive. Anyway that scene has certainly isn't very reassuring to the readers.]
Otto of the Silver Hand, by Howard Pyle, was published in 1888, and so ought to be a safe Victorian era children's story. But it is set during the "medi-evil" part of medieval history. Otto gets a silver hand to replace his hand chopped off when he is only eleven.
Here is a link to a question I asked about a children's book I read long ago:
In this unidentified children's book, two communities of supernatural beings, one of elves and one of fairies, are almost exterminated in a bloody battle in which hundreds or thousands are killed.
And of course that reminds me of a more famous children's novel, The Hobbit, by J.R.R. Tolkien, in which there is a climatic battle in which thousands of persons, Humans, Dwarves, Elves, and Goblins, are killed, some of them characters that the reader got to know during the story. And a scene where a severed Goblin head is on display. And a scene where a town with a population of hundreds or thousands of Humans is destroyed, and many of the people are killed.
And speaking of Tolkien, his first, unfinished and unpublished, attempt to write about his "legendarium" was The Book of Lost Tales, an early version of the Silmarillion written as a children's book. So if you have read the Silmarillion or The Children of Hurin you might be shocked to learn that Tolkien put in an early version of the tale of Turin in a book intended for children.
The second Oz book by L. Frank Baum, The Land of Oz (1904) had an ending which was shockingly unexpected, and which some readers might have thought to be a very dire fate for the child protagonist and others a glorious reward for them - opinions would vary a lot.
The Land of Oz was adapted for television as early as the September 18, 1960 episode of The Shirley Temple Show.
One of the first children's science fiction novels I read was The Voyage of the Luna 1 David Cragie (Dorothy Glover) (1948) where two children stowaway on an unmanned rocket to make the first trip to the moon.
The moon has an atmosphere in that novel, despite astronomers at the time being certain it doesn't. The lunar atmosphere is not breathable, so the kids (and their dog) have to wear breathing masks and use bottled oxygen when they explore outside.
And when the kids get lost and can't find their rocket, there is a scene where the boy worries that he may have to sacrifice his dog to give oxygen to his sister, and worries they will all die anyway if they can't find the rocket in time.
I remember that the children's room of my local library had a bunch of Robert A. Heinlein juvenile science fiction novels. And many of them had violence, and some of the young protagonists killed people in various conflicts. One, Have Spacesuit--Will Travel (1958) had a scene where an entire species of intelligent beings was condemned to extermination.
The children's room also had some novels in the Winston Science Fiction series for juveniles.
One, The Secret of the Ninth Planet, Donald A. Wolheim (1959) featured what appeared to be the total extermination of a species of intelligent beings by the protagonists.
Another Juvenile science fiction novel from the children's room was Raiders From the Rings, Alan E. Nourse, (1962), which opened with a prolog involving the killing of a child. The main story had an exciting action scene early on where the teenage protagonist goes on a raid to kidnap a girl to be his bride - not exactly the most ethical procedure.
In Mission to the Heart Stars, James Blish, (1965) Earth makes contact with the galactic government and faces the possibility of war with it. In the last scene one of the protagonists suggests sending dolphins, recognized as intelligent beings, to a water planet belonging to the galactic government to attack the octopus like natives, saying the dolphins should eat them up.
He doesn't consider the possibility that the octopus like natives might have weapons they can handle with their tentacles which might slaughter the dolphins sent to their planet. And he doesn't seem to care that if his proposal works it will be not merely genocide but "specicide". He suggests creating a situation where people eat people.
I have often dreaded the possible discovery that both giant and colossal squid and the sperm whales which prey on them are intelligent beings and people. What could we do if find that many thousands of people are eaten by people of another species every day? And yet that character proposed to create such a situation.
I haven't read many books for children or teenagers since those days, but I hear that one very popular series, the Harry Potter books, has a lot of death and violence and a villain so sinister he is called a "dark Lord", though I think that Sauron would laugh at that comparison.
One recent novel for young readers I read was Red Cap, G. Clifton Wisler (1991) based on a true story of the Civil War. Much of the story happens in the Andersonville prison camp.
As you may remember, Treasure Island by Robert Louis Stevenson (1881-1882,1883) has violence and crime. And when I saw the Disney movie Treasure Island (1950)on tv as a child, I was impressed by the violence, especially when Jim fights Israel Hands.
A lot of other Disney movies from that era had considerable violence.
I remember watching The Great Locomotive Chase (1956) in a theater, a film where the protagonists' mission is largely a failure and some of them are killed.
I also saw Tonka (1958) in a theater. A lot of people are killed, including named characters, in that movie, since it climaxes with Custer's Last Stand.
I also saw Davy Crockett at the Alamo on the Disneyland tv program. And obviously the protagonist and his comrades are defeated and killed at the Alamo in that program.
You would expect television programs for children would avoid what might be considered dark or controversial themes.
In the sitcom My Two Dads (1987-1990) the protagonist was a girl being raised by two men who were lovers of her deceased mother - nobody knew which was her biological father. That set up would have been considered unthinkable a few decades earlier. The girl often called them "dads". As society marches on, nowadays when a kid mentions "my dads" or "my moms" in a children's tv show, they mean a gay or lesbian couple who is raising them. Something unthinkable decades earlier.
In "Adventure Time" (2010-2018) on the Cartoon Network, there are some rather dark subjects, such as the atomic war which devastated the land a millennia earlier, and the tragic backstory of the Ice King. The protagonist Finn believes he is the last surviving human.
In Henry Danger (2014-1020) on Nikelodeon, superhero Captain Man starts out pretty good but gets more and more childish, self centered, and irresponsible over the seasons, so that some viewers might fear he would turn into a supervillain. The trend continued in the spin off Danger Force (2020-).
In the June 19, 2021 episode "Manlee Men" there is a transgender kid character, portrayed by a transgender kid. Something unthinkable decades earlier.
A number of people, human and otherwise, are killed in Wizards of Waverly Place 92007-2012) on the Disney Channel.
The protagonists, young wizards in training, are taught many spells of great power, spells to immobilize other people, spells to instantly teleport great distances, spells to reassemble broken objects, spells to bring inanimate objects to life, spells to travel in time, spells to wind time back over and over again until you get events right, and so on.
With such powerful spells, the young wizards in training can never find themselves in situations where it is necessary for them to kill. Therefore whenever they kill, it is voluntary and unnecessary on their part. So naturally you would expect that they never killed anyone on the series, but you would be wrong, the young protagonists did kill people of various types in several episodes.
The climatic scene in "The Good, the Bad, and the Alex", on May 7 2010, a date that should live in tv infamy, ended with the young protagonists talking and joking happily, while on the floor around them were scattered many pieces of a girl who had been alive just minutes earlier.
The character of Emma Ross was depicted as a good girl in Jessie (2011-2015) and the first three seasons of Bunk'd (2015-2018) on the Disney Channel, but in "We can't Bear it!", June 18 2018, Emma showed a shocking disregard for the welfare of a child.
In Gabby Duran and the Unsittables (2019-2021) on the Disney Channel two of the main characters are Gor-Mon, blob like aliens who can shapeshift and are usually seen in their human forms. In "Tailoring Swift", March 6, 2020, one is captured by other aliens who plan to skin him in Gor-Mon form, since Gor-Mon skin is a valuable fabric. A very disgusting plan.
Of course in real life, humans have often hunted apes, elephants, and cetaceans for food and for profit, and members of those species might possibly be intelligent enough to be considered people.
And that reminds me of a children's book I have read about, White as the Waves Allison Baird (2011). The protagonist, White as the Waves, is a rare albino sperm whale, in the era when humans in sailing ships hunted sperm whales and cut up their bodies and boiled their blubber to make whale oil. White as the Waves defends his people, fighting against whalers, and becomes known to humans as Moby Dick.
The protagonists in The Villains of Valley View (2022-) on the Disney Channel are a family of supervillains on the run from the League of Villains, and a teenage friend.
Thus there are scenes where three kids fight with superhero/supervillain weapons, not caring about possibly killing someone, where a kid attacks a supervillain in High School, and the watching kids applaud his attempted lynching, where a kid agrees to his father's plan to trap and disintegrate someone, etc. And in "No Escape" November 2022, two of the characters apparently kill people.
As you can see some stories and tv programs for children do have rather intense, dark, or controversial situations.
And I expect that different publishers will have different standards for their stories for young readers.
As a general rule, print media can get away with a lot more than visual media (film and tv) due to the fact that it's "theater of the mind" means that the reader is imagining the visual aspect of the world and will thus add as much graphic details they are comfortable with provided you do not go into graphic detail yourself. For example, the Animorphs series, a popular scifi series from the late 90s for late elementary-middle school readers, regularly featured scenes where the protagonists had limbs severed or witnessed someone else suffer from severed limbs (It helped that in the case of the protagonists, the process of changing into animals involved DNA, so they could recover from missing limbs and critical wounds so long as they could morph.). Early in the series run, one character (who was likely 13) describes a scene where she is chased by older men who seemed to be trying to rape her (Never explicitly stated). Harry Potter, while initially tame, matured with it's initial target fans, with Book 4 clearly marking a progressively darker tone in the narrative that continued until the conclusion of the series.
The other reason for this is that most parents, upon seeing their kid reading instead of playing a video game or watching TV, are not going to question what the kid is reading and will just be grateful it's something, so the moral guardian scrutiny and outrage is not as strong as those for kids shows and films.