Finn's a failure, at necromancy and life in general. "It's not my fault," he'd insist, looking deep into your eyes as he lifts your wallet. You'd catch him, of course. Because he's a failure.
Veruca, on the other hand, is competence personified. She has to be, working as a Reaper directly for the Prince of Hell. When Finn shows up in a stolen sport coat and uses Veruca as cover from his murderous mistress' glowering goons, she finds the one thing she may not be so good at: resisting Finn's handsome face.