The Conrad Chronicles — Heather Hobson

Zeplan of the House of Vasilis suddenly abandons training his niece, Lucy Gloria Vasilis Lucas, on how to use her Conrad powers. Unbeknownst to his niece, Zeplan was ordered to return to his home world, Aleron, by his father, whom he hasn't seen for more than a millennium. Lucy, now left alone to explore her increasing ability to use energy, takes jobs as a gun-for-hire in the Moulton Galaxy. After one horrifying mission, she acquires an agent, who helps her join an elite group known as Hawk's Men. Soon Lucy learns they aren't the villains reported to be by her agent and finds herself in a deadly situation, as she was hired to assassinate them and is now in love with their leader, Troy.