ive said this once and i will say it again, grady is the most nuanced character in KOTLC. Purely from just how he is written in canon- there is so much we can draw from his character with little inference.
On the one hand, you have a walking tragedy: he manifested one of the rarest and most dangerous abilities in the lost cities at a young age, he lost his daughter to her fiance, (if we're talking theory, he may have been in the neverseen), you can't help but feel sympathy for him.
But then- you realize something terrifying.
Gisela and Vespera are right.
Grady is the most ruthless elf in the lost cities.
But he's also one of the kindest.
Despite the danger it poses, he and Edaline adopt the Moonlark, they put themselves at risk. Despite everything been through, they willingly give their love to a girl who needs it. That is one of the kindest acts someone can pull off.
However, as alluded to earlier, there's another side to him. Despite how concerned, kind, and thoughtful he is; he is also vengeful, impulsive, and distrusting.
Let's look at Everblaze again. Partially because it's the best example of his darker nature, partially because I have it on hand right now, partially because it is my favorite book in the series.
In Everblaze, Grady's vengeance and impulse is seen in full. Take King DImitar, for an example. Sophie was going to be taken away; and Grady jumped in. He believed it to be the right thing to do; and believe me it was, but there is a dark tone to it. A feeling of impulse; that he wasn't truly thinking at the moment. And he almost violated the treaty, if it wasn't for the Councillors coming to his defense.
This scene serves as subtle foreshadowing for later and sets up something very important about Grady:
He could kill someone if he wanted to. And he knows that.
But what could push him that far? Well, there is an answer to that, an answer we later find out:
When he finds out the true circumstances to Jolie's untimely demise, his sheer ruthlessness is demonstrated. There's a deeper level to this however, it is his underlying fear of being taken advantage of showing to its surface.
Brant took advantage of Grady and Edaline, and that is the biggest injustice to Grady. Because it's what he has been fearing, it's why he had closed himself off to the world.
That fear causes the sheer level of terror that is caused in Grady. Terror that builds into his impulses, which causes him to go out to find Brant, with intent to kill.
That's why he doesn't want Sophie to come with, he doesn't want his daughter to see the monster he was about to become.
The monster he believes himself to be.
It's not just Everblaze, but a feeling that permeates his character and his choices.
His distrust of Keefe stems from two things:
The similarities he sees between himself and Keefe (the sense of humor, the blond hair, and later in the books; the ability of control).
How that, in a way, is all Grady has ever known.
Elves manifest young. Meaning that he has spent a majority of his life being distrusted by his peers, as well as distrusting the world and fearing someone would take advantage of him.
So when there's a talented but terrified young kid that needs his helps; whether through adoption or through training, he obligies.
Because he sees himself so much in that situation. Because of that deep feeling of kinship, he feels a need to take care of people in that situation.
Grady's empathy trumps his distrust.
And that's why he starts helping Keefe. That's why he adopts Sophie.
tl;dr: grady's character absolutely FUCKS why does no one talk about this???
also he is hotter than hell and i will fight people on this