Julie's older sister, Cassie holds a secret from her close friends Shawn and Jaxon: she didn't just get a lucky break to cater for Redborough's crime boss, she actually works for Ivan Vance.
True, hers a low level job that doesn't involve any criminal activity, and she's barely on the kingpin's radar, but that doesn't mean Shawn and Jax will forgive her if they find out. In short, Cassie needed money for law school and had nowhere else to turn. Her friend and mentor, Henry, takes pity on her struggles and connects her with Vance, who lends her the funds she requires with one condition: she takes a job at his catering business and pays him back every single penny in timely payments. He'll keep it interest free - and she'll keep her life. Desperate to please her strict parents, Cassie agrees, and everything works out fine. Until her sister is gunned down. Feeling responsible, just like Henry, Cassie teams up with Shawn and Jaxon. They create Grim while she uses her inside connections in Vance's business to poison the crime boss two years after Julie's death, which is the start of Grim Ambition.
Not much is known about Cassie's personal life. She obviously has feelings for Shawn, or at least just "wants his bone," as Jaxon puts it. She's frustrated when Shawn turns her down, though, saying she's too much like his sister and he knows Jaxon is interested in her. Cassie shows that she cares deeply for Jaxon and what he's been going through since Julie's death, but that's it. She is kind and caring toward him, letting him know she's there if he needs any kind of help.
Outside of Shawn and Jaxon, Cassie tends to go out with her female friends, and no other male love interest is mentioned.
Cassie is mentioned in passing throughout the majority of Grim Inception by Henry, who is her friend and mentor. It is learned that Henry got not only Cassie involved with working for Vance, but her sister, Julie, as well. He ensures the reader that he wasn't aware at first that even low-level employees can never leave Vance's grip once they are "hired," and shows regret later on in the story for ever getting them involved. Whether or not this is true, we do not know at this time. During the shootout caused by Alex that kills Julie, Henry hides behind shelter with Syrus, also a Vance employee, and they both survive. Once in the clear, Henry finds Julie's body and falls to his knees, thinking only of the promise he'd made to Cassie earlier that day: that he'd protect Julie. Distraught, Henry becomes bent on revenge, promising Cassie he will help her take down not only Alex, but the crime boss Ivan Vance himself as well.
Cassie is first seen in Grim Ambition when she regroups with Shawn and Jaxon in Shawn's basement after he returns from the attack on Vance's top men. It is revealed that Cassie was the caterer that slipped the crime boss the poison, slipping a fish called fugu into his sushi to do the job. She is immediately concerned with Shawn's face, which is bruised like crazy from the metal pipe Grant hit the vigilante with during the attack. Shawn shies away from her touches, much to her disappointment, but everything is interrupted when Cassie receives a message from Henry stating Vance was going to survive the attack on his life. Furious, Shawn mentions going to the hospital where the crime boss is being treated. Cassie, along with Jaxon, convinces him not to, knowing it would be a death sentence to even try.
Later on, the trio is having lunch at Ralph's Pub where Cassie and Jax discuss their concerns about Shawn's impulsive behavior while fighting as Grim. During the conversation, Cassie also turns down Shawn's offer to lend her money to go back to law school (which she'd really use to pay back Vance, but he is not aware of that), stating that money is his from the settlement after the death of his parents.
We also learn that Cassie is terrified that Vance will find out she poisoned him, so she reluctantly takes Jaxon's offer to stay at his place until things calm down. This continues until she receives a comforting message from Henry that all is well and her name has been cleared, that she isn't in any danger of Alex or Vance finding out what she did. Relieved, she moves back home, much to Jaxon's disappointment. Of course, the reader, however, learns that Henry's message was sent under great duress, and that Cassie as well as her friends and family aren't safe at all.
Jaxon continues to try to get Cassie interested in him, but to no avail. She agrees to spend time with him, but makes it clear she doesn't have feelings other than friendship and concern at his continuous bad moods and sleepless nights.
Eventually, when she agrees to a few drinks at The Ruffian with him the night before Thanksgiving, she realizes Jaxon is much worse off than she thought. She and Shawn discuss the issue over the phone, which prompts Shawn to head over to The Ruffian to see if he can help cheer his brother up. Instead, Jaxon stays a whiny little bitch, even after Cassie brings up the pair of men that seem to be watching them from the bar. Shawn asks her to describe them. She says one’s older, maybe in his fifties and has a greying beard (Marcus) and that the other is black and looks like he’s in his forties (Grant). Jaxon thinks they're just checking her out, but she feels uncomfortable enough to urge them to change venues, and they head over to Topeka Tap. Unfortunately, the mysterious men follow them, which truly freaks Cassie out and begins to cause suspicion in the brothers. They hail a cab and head over to Sway, even though Shawn states he'd rather go home. At the dance club, he loses track of Jaxon and Cassie and, due to the shots his brother forced on him and vivid visions of his mother's death, he ends up on the floor covered in his own vomit. Jaxon and Cassie find him like this and take him home.
The next day, we learn Cassie left in the middle of the night. Jaxon is worried about her but Shawn insists she's fine, and that they have to discuss the issues of the previous night.
We don't see Cassie again until weeks later, after things have calmed down in the trio's lives. They are meeting up at The Dirty Martini, which just remodeled and is having a grand re-opening. At the bar, they meet Emma, who Shawn instantly hits it off with, much to Cassie's disappointment. Of course, those who have read the book know that Emma is a plant, and this is the beginning of a downward spiral into chaos for everyone involved, good and bad alike.
Dawn of the Wraiths: A Grim Origin
Yeah, like I'm going to give THESE spoilers away. ;)