Mac had a close friendship with fellow detective Stella Bonasera and was suitably concerned when she was held hostage in her own apartment by her deranged boyfriend, Frankie Mala, in 2.21 "All Access" and eventually forced to kill him. After she is discharged from the hospital, he "orders" her to take some time off and get counseling before coming back to work. He once tells Stella he wouldn't do this job without her. The two exchange Christmas and birthday presents, and because of this, Stella is mistaken to be Claire Conrad by Reed Garrett when she leaves Mac's home after giving him his birthday present. Mac is also the first person Stella tells about the possibility that she may be infected with HIV (episode 3.17, "The Ride In"). She also informs the press that there is no one inside or outside her profession that she trusts more than Mac Taylor.