I've been pondering Nate's backstory a fair bit, and especially thinking of ways to parallel with Gale's. I really don't know ThAT much about the BG lore but I've been poking around on the Forgotten Realms wiki to at least have a rough idea of things
In this universe Nate's father Cato was a Drow, which kinda sucked for Cato. Sorry man. Growing up in Drow society made him vicious and disillusioned and manipulative.
Nate's mother Adlevia was a human Druid from a small Circle - raided and destroyed along with the patch of woodland they loved, with many taken into slavery. She survived the longest out of those captured, owing to the ferocity of her survival instinct. Long enough for a spark between her and Cato to inspire him to abandon his homeland and elope with her - at great personal risk to both.
They fled to deep forest, strong in magic and far from civilization, where she could protect them from all but the most determined of incursions, and it was here Nate was born, where they hoped he would be safe from their own pasts.
But Cato and Adlevia had lived through real horrors, and a lifetime of pain and resentment was hard for Cato to put aside. So was all Adlevia had lost. They were in love, but it wasn't an idyllic marriage. Fights were frequent and not always hidden from Nate, who often felt compelled to intervene. Cato could be outright abusive in the name of preparing Nate for life. Adlevia was stern, demanding in her lessons on Druidcraft. They wanted to protect Nate - but they wanted him to be able to protect himself, too.
Thus self-doubt seeded itself in Nate at a young age, and he couldn't help but blame himself for his parent's strife -- as many small children are wont to do.
Cato died while Nate was in his adolescence, Drow have long lives and long memories and the slight of the lover's escape was unforgivable. He fell in defense of the wood, and his family.
Widowed Adlevia lived to a goodly age, but she was human, and made no attempts to extend her life beyond it's natural span. Even raising a child who grew so much more slowly than a human child might. She was elderly before Nate was old enough to live on his own, and gone from him before he would have liked. But she'd taught him to survive.
Nate took naturally(hah) to Druidcraft. His friends growing up were the beasts and birds and dryads of the wood. He wandered through it without fear, and took a particular mastery to Wild Shape. He would run with the wolves and flock with the sparrows.
In spite of his parents efforts to prepare him, Nate had a soft heart. He would mend wounded animals and restore withering plants, unable to watch them suffer in silence.
He found, as a young man, a wounded hind. Ravaged by some predator she'd escaped, only to have her strength fail her.
Most would have killed her as a mercy. It was only a hind. Adlevia would have urged Nate to if she'd known - for death is a natural part of the cycle of life, and trying to mend such grievous wounds might only extend the hind's suffering without saving her.
Nate wouldn't. Couldn't. For weeks he laboured tirelessly to care for her, until she could stand again and her pains were but a memory.
It was in this way he drew the eye of Mielikki.
She came to him as a woman, russet-haired, soft of step. And they ran wild through the forest together for a time. She was the wind in the leaves and the songs of the birds and the babble of brooks. Of course he loved her. And because he loved her so dearly, she loved him in kind.
He did not at first realize it was a goddess he had taken up with. These were arguably the happiest years of Nate's life and he would have been content to live out the rest of his days with her. But of course, all things have seasons.
Mielikki knew Nate was mortal, even if Drow blood made him longer-lived than most, and that, ultimately, he belonged with his own kind. He needed to be part of nature, not simply alongside it. She told him as much. Their tryst ended amicably, Nate accepted her wisdom, even though it hurt.
From there he began to wander, leaving the safety of his woodland home for forests unseen. Always he felt Mielikki watching over him, though, and took solace in her continued favour.
A Druid with no Circle, he aided man and beast alike where troubles found him. As decades passed he developed a reputation as a Folk Hero - how could he not, a half-Drow appearing from the woods with wolves at his heels, helping strangers in unexpected - often bloodless - ways, and vanishing again.
So it went, until the Nautilus, and everything Nate cherished both in the world and in himself would come under siege.
