Christina Logan is the mother, previously assumed as sister, of Robert Logan and the assailant of his therapist, Greta Heints, who endangered Robert's mental health by neglecting his assumption they were in a relationship.
Background[]
Christina was born to Victoria, an extremely religiously zealous and physically violent mother with a severe misandry, or hatred of men, resulting from her husband and Christina's father leaving the family. She was always terrorized by Victoria to believe boys and men "were dirty" and degraded Christina to try and make her never be near boys and have Christina never let them get near her. That only encouraged Christina to hate her and freely date and have sex with boys as she liked, eventually getting pregnant with her son Robert when she was fourteen. When Victoria found out, she nearly beat Christina to death but made her keep and give birth to Robert. The moment Robert was born, she stole him from Christina and made her stay with family in Minnesota, threatening her to never return and never mentioning her as a child to anyone.
When Christina came back seven years later and was horrified to find out Victoria tortured and humiliated Robert for the time she was alone with him, insulting his self-worth and making him "pray for his sins" just from being a boy and physically abusing him by scrubbing him raw in the bath and tying his genitals off repeatedly to cut off the circulation. Out of heartbreak and a vengeful rage, Christina ran with Robert out of the house before setting it on fire with lighter fluid as an accelerant, killing her mother and his grandmother in the flames while she was engulfed inside. From then on, Christina never left Robert alone and vulnerable and vowed from then on to protect him, with Robert keeping the secret of the murder she committed for years. She always called herself and Robert "brother and sister" from then on and grew up into a medical crisis and rehabilitation specialist, while Robert was receiving treatment for his trauma from Dr. Greta Heints, a therapist and forensic psychologist specializing in regressive memory recall and psychodrama reenactments. Unfortunately, Robert ended up with transference, or affection for his therapist, especially when Heints would make him listen to graphically suggestive tapes to project on her as his "mother" in their sessions. Heints saw she overstepped and tried to transfer Robert to a male therapist, which he considered "breaking up". He had a nervous breakdown and called Christina in devastation, Christina admitting him overnight in a psych ward as an emergency precaution. Christina found the tapes and, hearing what abuse her son went through that endangered his sanity and spirits, as well as worrying the two were in a sexual relationship, snapped and planned a revenge on Heints for the violation and humiliation Christina figured she put Robert through, hoping she wouldn't be in a state well enough to reach Robert again.
Mother[]
Christina called Heints over to a crack house she would find drug addicts she treated in, "the lowest place" she knew, under the false pretense of Robert "being in trouble". When Heints and Christina got passed the watchman, Javier Medina, for the dealer there that night, Christina threw Heints on a mattress and bound her with duct tape, before tearing her clothes, viciously kicking her genitals, and beating her so badly her head trauma left her amnesic of the night. When two clients, Dominick and Jordan, take a wrong turn and find Heints, with Dominick close to raping her while she's knocked out, two narcotics agents barge in and arrest the two, finding Heints sprawled on the mattress still with her clothes torn down to her lingerie.
Heints' patients are first suspected, but they're soon after cleared, with one being sentenced again, and Robert becomes the prime suspect when multiple calls from him are found to have been to Heints' number and her office is burglarized by him to steal the tapes of their sessions to take home and feed his obsessions. The detectives have intentions of interrogating him when he slashes his wrists and Heints appears riding with him in the ambulance, barring the detectives from questioning him to prevent his mental breaks from getting worse. Christina is questioned, where she voices her opposition against Heints and how she isolated Robert for her therapy and took his chances of being a success. When Stabler and Benson mention Heints' assault and Robert's a suspect, she gives his alibi: Robert's nervous breakdown that night and his emergency crisis psychiatric admission.
Since he checked out against medical advice for five hours and it still leaves a window of opportunity, he's still arrested on suspicion. Because he's not competent to stand trial in the moment, his incompetency defense is challenged in court. When Heints testifies and denies the sessions are a "relationship", Robert has a breakdown and tries to make out with Heints, begging her to say she "loves" him while he's restrained. Christina comes into the precinct after the trial's a bust and plays the tapes Logan stole she found in his apartment. The tapes' language matches the delusions Robert was spouting, but when Heints is interrogated, she still denies it was more than therapy, lamenting in her own attempts to make breakthroughs, she made Robert too enthralled in the psychodrama. Munch and Fin go back to Medina to put Robert at the scene that night, but he doesn't; he puts Christina there that night instead. Her prints are found on the duct tape used on Heints, so she's brought into interrogation. She tries to deny, but when the forensics are revealed, she confesses to finding the tapes and luring Heints to brutalize her. She then presses charges on Heints, but the team has more concerns when they look up Christina's claims that Victoria died of cancer and find the truth about the fire. Questioning Robert, Dr. Huang questions Robert about his abuse and the fire he kept secret about, and he confesses Christina set it and made Robert keep silent for years, having buried the secret in personal turmoil for too long.
Christina is confronted in jail and tries to lie, saying she reunited with Robert after Victoria died in the fire. But when Stabler and Benson tell her they know she saved her "brother", she reveals the truth: Robert's her son, kept from her and terrorized and abused for seven years, because Victoria hated Christina being promiscuous and giving birth to a boy. She leaves closing the interrogation with "Wouldn't you do the same thing for your son?".
Christina's found guilty of murder, sexual battery, obstruction of justice, and reckless endangerment and is sentenced to life without parole. It's unknown what happened with her charges against Heints.