Learning of the pipeline
When a police cruiser camera apparently caught Detective Eddie Thawne shooting two officers without warning, Cecille interrogates Thawne at CCPD. Despite Captain David Singh unwilling to believe Thawne to be capable of murder and Barry Allen pointing out lack of powder burns on his clothes, Cecille refused to be moved. Later, she, Singh and Barry watched security footage of the Flash fighting Hannibal Bates, who shapeshifted into multiple forms, including Thawne's. Cecille remarked that law wasn't ready for meta-human criminals. After dropping the charges against Thawne, Barry provided evidence for Cecille to exonerate Bates' other victims he framed for his crimes.
Working alongside Joe West
Over a year later, she informed Joe that the D.A.'s office had no information on Alchemy and guessed that his inquiry was meta-human-related. Later, she and Joe visit Rosa Dillon at Iron Heights for information on the whereabouts of her boyfriend Sam Scudder, who gained power over mirrors, according to a former associate of Leonard Snart, who was assaulted by Scudder. As soon as they were done questioning her, Scudder appeared and broke Dillon out using meta-human powers. After Scudder and Dillon were apprehended by the Flash and Jesse Quick, and sent to Iron Heights, Barry assured Cecille and Joe that Scudder couldn't Mirror Master his way out because his cell was lined with an anti-reflective material. Afterwards, she asked Joe out on a date, but he declined, stating that he had movie night with his kids.
Cecille and Joe meet again during Christmas when they toast to their grandmothers (and their respective eggnog recipes), then they kiss. Cecille is seen again with Joe, before Iris and Wally steal the papers on arms dealer from their father.
Later, Cecille goes for coffee with Joanie, her daughter in the company of Barry, Iris, Wally and Joe before Clive Yorkin arrives for Joe. Wally as Kid Flash succeeds to flee him and save the rest of the group. Cecille and Joe go on another date with Barry and Iris.
Love relationship with Joe West and ally of Team Flash
Cecille and Joe are seen again after a race and they kiss before Joe receives a call, forcing him to leave Cecille. Then Cecille is kidnapped by Killer Frost in exchange for Tracy Brand, the only person who can stop Savitar. But her plan fails and Cecille is saved. Soon after, Joe admits his love to Cecille and tells her about Barry and Wally's alter egos.
Soon after this Barry went through an experiment to try and prevent himself from creating new memories in an effort to stop Savitar from using his knowledge of the future against the team, However the experiment failed and left Barry with temporary amnesia. At the same time the trial for Lucious Coolidge was moved to an earlier time. This caused Cecil to call in Barry as he was the CSI officer assigned to the case because he needed to testify in court however he still had amnesia, much to her dismay. She attempted to work with the problem until it backfired, causing Coolidge to walk free and terrorize the city again.
Cecille was talking to Joe about how they are going to live their life. Cecille makes the decision of moving to a different home. But when Hazard releases bad luck to many, the West Residence falls apart slowly. After Cecille puts new coats on the wall. He tells her that they don't have to live here, Cecille has a change of heart and wants to live at the West residence telling him "I'm pregnant." Joe didn't know how to react.
- High-level intellect/Expert lawyer: Cecille is very intelligent, as the district attorney of Central City, she is an excellent lawyer; as Cecille has successfully prosecuted many criminals and presumably has never lost a case.
- Network: As the district attorney, Cecille has access to the resources of her office and the Central City Police Department.
Behind the scenes
- In the DC comics, Cecile Horton was the defense attorney for the Flash during his trial for the murder of Professor Zoom.