The dark wizard Shayde wants an apprentice, so he tries to summon the most powerful untrained wizard in the world. What he gets is a young girl from our world, where magic doesn’t exist and science rules supreme.
Idea A – Charlene actually becomes his apprentice, only to discover that her new tutor is an evil bastard and has to rebel against him.
Idea B – convinced that Charlene is useless, he throws her into the slave market, where a good wizard finds her and frees her from captitive. Charlene has to go to magic school to learn how to harness her powers, which brings her into conflict with her kidnapper…
Chris
The Chrishanger 
Idea C – Shayde inhabits a truly crapsack world, and Charlene comes to realize that his “evil” ways are a necessity to survive, and to bring a semblance of order to it. As a result, she becomes a knowing and willing apprentice, all the while struggling against her conscience. You can create a compelling antihero(ine) in this manner, which should also add extra depth to the concept.
Interesting. Might be difficult to pull off though.
Chris
How about idea D. He thinks she’s useless and is planning to throw her into the slave market. But she reminds him too much of his dead and lost daughter. The reason he became an evil SOB in the first place. (she thinks she’s going to be trained as a real actual wizard in some creepy version of hogwarts)
He takes her to the slave market, intending to sell her, but doesn’t actually tell her know that going in.
When he gets there, he’s on the edge of the steps leading up to the platform where the slaves are auctioned, with a crushing grip on her forearm, so she won’t get away. She’s just starting to get scared and the look in her face makes him think how his own daughter would be her same age right now and he just can’t do it.
So he gruffly tells her to look good and hard, this is the wonderful world created by the so-called lords-of-light and mighty White Wizards of the Second Order. They live up high in their floating ivory towers and the dregs of society are cast out to live however they can. Then he points to the Knightly Order of all that’s Good and Right and points out how they patrol the very city this slave market thrives on the outskirts of. Even if they won’t lower themselves to trade in slaves they enable its activities.
Maybe he makes an impulse buy. Getting his ‘apprentice’, who he hasn’t told is completely useless and unsuited to being an apprentice, a maid servant. His ultimate plan to send her away, so he can get her and her uncanny resemblence to his lost daughter and ex-wife out of his tower and stop messing with his head.
He’s on the way back to his carriage with unknowing non-apprentice and new slave servent in tow when he’s confronted with the big reveal. Either priests, other black wizards or some magical lackey of the White Order confront him. (or better yet a series of encounters one after the other) They demand he turn over the ‘boy’. The Priests demand he sell them his new apprentice, they’ve augured the future and seen great calamity for the Kingdom of Light and their temples if he completes his training and so they offer 10,000 ounces of gold to hand him over for sacrifice. A pair of Good Wizards show up demanding he hand the ‘boy’ over. They’ve scried through (what they mistakenly belive to be protections against scrying set by our Black Wizard) ‘his’ aura and ‘his’ talent for Adjuration, (counter spells, dispelling magic and shielding, etc) is through the roof. Such talents are normally swept up by the Order first, they can’t imagine how our Evil Guy has hidden his apprentice for so long but they are here to claim ‘him’.
Then a small group of Journeymen Level Black or Grey Wizards show up, demanding the Apprentice or a piece of the Action. They’ve been watching and seen how the White Wizards and Kingdom of Light Priests want this new ‘boy’ and how our Evil Guy drove them off. He’s weak now, so either he hands the boy over or let them join his ‘Cabal’ and charter members of his new ‘Black Council’.
Our guy is a loner by choice and by the fact other black and grey wizards don’t trust him. Maybe he’s a failed White Order Apprentice or Journeyman. He’s about to tell the Black/Grey Journeymen to go to Hades, when he realizes, All his enemies think his new female apprentice is really a boy (which should be impossible unless she really does have a natural talent for Abjuration), and that they all believe having her in his hands will be catastrophic for their interests.
Suddenly he’s thinking he missed something when he hastily scanned her aura the first time. And if keeping her around gives him a chance to put a spoke in the wheels those despised White Order, nose in the air, Pure Magic fools, he’s all in.
Now he just needs to recall enough of the man he used to be, before his daughter was lost, his wife left him, and everything went straight to the pits in a downward spiral of hatred and hard choices. All so he can convince his new Apprentice to stick around and become a ‘real’ apprentice. Maybe someday soon, he’ll be the one jumping those mighty White Order Wizards in back alleys and getting some answers, not to mention a large helping of revenge along the way.
Then have Charlene start to see him. Both the good, which he thinks is no longer there. As well as the bad, which most definitely is, this is not a nice guy, if ever he once was. He makes deals with Demons, Necromancers, the scheming little pip-squeaks in the Cabal, as well as a host of more benign but greedy creatures, all for his obsession with revenge which he tries to hide but can’t entirely. On the other hand she’s seen just what the White Wizards have done to the world and allow to go on, they aren’t the squeaky clean guys they pretend.
Which way will she jump. Where will she go? And is her new maid really a secret Witch of the Twisted Grove, a powerful organization of secret female magic users? Plus if these White Order Wizards really scan everyone for magical talent, why aren’t there as many female magic users as male ones? Conspiracy followed by conspiracy, tempt, taunt and exasperate our female heroine as she tries to untangle what’s really going on in this very much dark and non-unicorn and ponies fantasy world gone wrong.
The Deposed King
Now that’s a cool idea. I’ll steal it.
Chris