Separated at birth from her twin sister by Mercs working for Liam Cullen. Her kidnaping was a carefully arranged idea done by a powerful Demon Lady, who was competiting against a rival Demon Lord, for control of a powerful host body and Dominion over the New York Hell Zone. She put in plan the series of events that lead Liam to discovering Rebecca Reynolds's descendant was to be born to one, Vanessa Chandler.
Only it failed to mention that she would give birth to twins and the Mercs kidnapped the wrong one. Liam would train her until she grew up enough that he could see she did not look like Rebecca and therefore had the wrong kid. In his anger, he killed his men for failing him and tortured her. The Demon Lady would take over training and looking after of Young Cassandra as she didn't want her future vessel to be too damaged. Training in many forms of lethal armed and unarmed combat and brainwashing commenced.
All the while the demoness was take over the body of Vanessa Chandler, Robert Reynolds, JT Forbes, and Juliana Keaton. Stealing the different beasts formulas they each made, the super soldier one Vanessa used on Vincent, the upgraded beast serum Robert used on Vincent, the Mixed formula JT made that was used on Gabe. In addition, the demon made her own superbeast serum and had Juliana make a special superhuman serum that was grant all the same powers each of her test subjects had gain. The demon also got her claws on the firebeast formula used to make a fireproof beast, and she combined all the beast serums into one Mega concoction. She then injected the Ultra Super beast serum into Cassandra, followed by the superhuman serum and then took over her body. She had fed Cass her blood for many years to toughen her body up for this transformation and to make sure she survived the process.
Due to feeding Cass her blood, every single day since birth, her possession to Cass became permanent. Fused to her immortal human soul forever. Due to all the work she had done to get this far. She didn't realize that Liam had made a tape for Catherine. Detailing his plans in her abducting, his alliance with the demon and that he combined the tape the demon had stolen from Vanessa. A tape that talked about her having birthed twins and losing one at birth. He had the tape sent to Catherine after his death as a way to taunt her from beyond the grave as he was going to use the tape as leverage to make her marry him. Catherine would get the tape sometime after Vincent Killed Liam and the emotional downward spiral would begin.
At some point in time prior to the tape arrival. Catherine befriend and briefly partner with a British cop who was in charged of establishing the K 9 Divsion at her precinct. It would come out that she was a hellhound that had been sent to her due to a lie about her having family relation to Catherine, like being a long lost sister about the soul of Catherine's sister residing within her. Though it turned out it wasn't all a lie just a gross misinterpretation and later it became clear that Nina was sent to Catherine to help Cat find her missing twin sister and deal with the Demoness behind it.
They had some brief adventures together before she was task with dealing with the lies she was given. Nina kepted in touch with Catherine and told her to call upon her anytime she needs aid. Nina had told Cat that a reason she was extremely good at missing persons cases and finding her targets. Was that as a hellhound. She could track any human or demon target, anywhere on the planet. Once she was given a target to lock onto, it was impossible to hide from her. One could try to run but never stay hidden for long. Catherine called upon Nina for her help to Track Cassandra and help she did.
It was a bitter reunion to Meet Cassandra who was taken over by the demon completely. There was nothing Nina could do to exorcise the demon spirit within Cassandra, not without killing Cass or sending her soul to hell forever. So Nina instead had to fight the Demoness herself in order to defeat it and suppress it so that Cassandra could regain control.
Of course neither one of them knew of the brainwashing Cassandra had suffered or that it was still in effect and Cassandra went into assassination mode. Nina barely had the strength left to deal with Cass after shutting down the Demoness hold over her, but she pushed herself to nullify the residual demonic strength, Cassandra still had lingering and sent her into her normal human state. Nina collapsed unable to fight anymore and that left the bitter showdown between two sisters.
Catherine and Cassandra would end up fighting one another with Cass intending to fight to the death. It was a bitter fight on the top floor of a half finished skyscraper. Rain and lighting began to brew as the Demoness inside did not want to lose and tried to fight for control one last time. But through the battle a part of Cassandra was able to awaken, after hearing the tearful cries of the twin sister she never knew calling out to her, her hesitation to fight her, her proclaimation of sisterly love, was what finally helped Cassie to break through the Demoness' control and the brainwashing.
It came just at the right time for Cassie to see her sister with her own eyes. To say she loved her back and tears streaming down her face as she hated what the Demoness made her do and what it did to her. Course the moment of control would come a little bit too late, as lightning would strike Cassandra when she picked up a metal pipe to swing down upon her sister's head. The rain had made the floor they fought on slippery and Cassie took the full brunt of the lightning bolt, slipped and fell over the edge. She fell 50 stories to what might have been her death had not the Demoness in a desperate sense of self preservation, caused her host vessel to go full beast mode and demon mode, allowing Cassandra to survive the plunge to what would've been, certain death.
She suffered massive brain trauma and multiple compound fractures, burns, lacerations from the glass windows that were propped to the sides of the building for corrected installation, she suffered enough injuries that made the nurses and doctors wanting to proclaim her DOA. It was a miracle in their eyes that she was still after slipping into a coma that made her appeared Brain Dead. It as touch and Go but Nina was able to help heal her to the best of her ability and Catherine's love and prayers went a long way.
It was during this time that Nina was able to permanently deal with the Demoness inside of Cassandra.
Nina used everything she had to suppress the demon and let Cass's consciousness take over the demon's. Cassandra would eventually gain full control over the demon later on, after she awaken from her series injuries and fully recovered. The binding ritual Nina used would allow Cassandra to be able to transform into a demonic form at will and use the Demoness powers whenever she desired. She was turned into a Devil Lady, thanks to the Hellhound cop, Nina Lockhart.
After months in the hospital, Cassie would open her eyes and have no memory of her past or who she was. Memories that took a very long time to return. She stood with Catherine who was by her side every step of the way. Little by little a peice of herself, that would have been untouched by the Demon and Liam had she not been abducted, would slowly come back to her. She stayed with Catherine and the two of them slowly began to bond and make up for lost time. Eventually when Cassandra got better. She thought about what job she wanted to due.
Having been a theif, assassin, and gangster during her tenure with Liam and his Demon associate. She decided she wanted to put her abilities to good use. To use them against evil and protect the innocent. That would lead her to the decision to become a cop like her sister. A means to curb the demonic impulses she still had to contend with and the violent nature of the beast within. Fighting crime would allow her to channel her dual Demonic Beast nature to the benefit of humanity and not its detriment.
Following in her sister's footsteps she would joined the police academy and blew away the records held by former recruits. When she finally Graduated, she ended up becoming a rookie cop under the guidance of her sister and her sister former partner, Nina. Freshly graduated from the police academy, Catherine took her twin under her wing and would teach her everything he knows. Learning how to live with the demon inside of her was not easy but appeasing the Demon's taste for violence by using it on heinous criminals instead of innocent people, did wonders for her self control. Her beast abilities and demonic powers have proven an assets in her job.
Before meeting Catherine and the bloody fight between the two sisters that resulted in Cassandra ending up in the hospital and losing her memories. She worked as both a gangster, very skilled thief, and assassin. Having racked up quite a body count both during her demonic possession and before she got possessed. When she was being raised and trained as a killer in her childhood formative years. She was brainwashed very thoroughly and only the lost of her memories helped to undo the brainwashing. Her skills as a former criminal ended up being invaluable in her new career as a cop.
Her life now mainly focuses on trying to be a good cop and sister. She adores her fraternal twin Catherine to death! And was nervous to meet the rest of the Chandler family. But over time as she got to know the rest. She grew to love them deeply. Thanks to the love of family, the trauma she suffered at the hands of demonic forced becomes less and less as time goes on.