What's the Name of That Book??? discussion

Ok, so it starts off by the boy being chosen for his power to be i think an assassin. Powers usually belong to several different families, the boy had the power to push other people into doing things, there was another family who could predict the future.

Anyways, everyone wears gemstones around their ankle that captures their soul when they die, but if they aren't released they'll come back as zombies. Some king or something kills a bunch of people and doesnt release their bands so they will comeback and besiege the young mans family, the king had hoped to get the young man too. The zombies eventually catch up with the young man and the (assassin?) who had picked up and they fight for their life. The guy who picked up has control over lightening. There were too many and they were almost overwhelmed but then a (dragon?) in human form saves them, and the boy falls in love with her. She describes everyone's mental picture of theirself, how the (assassin?) who later becomes the boys mentor looks like a tall living lighteningstom within his head, but the boy, looks exactly the same - a sign of big power for some reason.

The (dragon?) is looking for her lost sister I think her name was katie or something. I think in the second book she finds out her sister is being enslaved by the healer guild as a tool to increase their power.
There are two books to this series. Its set for young adult/ teen audience. I read it several years ago, so it couldn't have been published after 2012

Assassin's Apprentice ?

Do you remember anything about the cover?

THATS IT!!!! THATS THE BOOK!!!! THANK YOU!

You're welcome :)