Javier Baez, better known as Tic-Tac, is the younger brother of Maria Baez and a known junkie. He and Maria were estranged for many years.
When they were younger, Maria looked up to Javi and they were best friends, to the point he wanted to stay back a grade and often protected her from bullies. That all changed when he got into drugs and became known as Tic-Tac as he would swallow anything that resembled drugs. After years Maria stopped wanting anything to do with him, cutting him out of her life. His drug use caused many problems for the family. Eventually their parents split up due to the stress of trying to keep him clean, his lies and stealing.
Maria and Javi came into contact again when he became the suspect in a murder, and in their efforts to arrest him Maria tackled him through a glass door. He then claimed that he had been clean for several months and was employed at CZE Tech because he was still good with computers. Once his employment was verified he was cleared as a suspect in the murder case.
Later it becomes apparent that the intended target of the murder was Javi, but when they go to interview him they find he has OD'd. It is then that they discuss needing Javi to act as bait to make a case against the real killer. He's taken to another location where he is almost killed before Danny and Maria save him.
He comes up again when a DEA shipment is hijacked and Maria is again devastated when it appears that he has returned to drugs. Upon interviewing him, Javi reveals that he became a mole for the DEA in an effort to make Maria proud of him again. When it appears that his status as a Confidential Informant was compromised, Maria and Danny track him by identifying the mole and raid the auto shop where the drug dealers are. During the raid Maria stumbles across Javi who steps between her and a shooter, losing his life to protect her.