Daniel Keller is the ex-husband of Nicole Keller and father of Luke Keller.
Background[]
When Daniel first met Nicole, he believed she was charming and brilliant. They later had a son named Luke. Overtime the relationship between him and Nicole fell apart after he began to notice her issues. Being a psychiatrist as well, he grew frustrated with her tendencies and need for gratification, and they divorced. As mentioned by himself, he tried to stay cordial but could not make it work. Not wanting to leave his son with her, Daniel fought hard to obtain custody but Nicole manipulated the judge in her favor leading to joint custody between them.
Motherly Love[]
During a hunting trip with his son, the two gotten into an argument and Luke decided to go home to his mother. However that night, Luke killed Trey Franklin, his best friend and the underage sexual partner of Nicole, at her direction by crying rape.
Daniel was notified by this event and arrived at the precinct to pick up his son. Daniel asked him if he was alright and inquired to the detectives does he need a lawyer but they told him Luke was free to go because it look like he was in the right for defending his mother. Relieved, Daniel proceeded to comfort his crying son.
Upon further investigation into Nicole, SVU discovered that she might have been sexually involved with Franklin and cried rape to cover her tracks. While SVU was interviewing his son after confirming their theory with another friend of Luke's, Ethan Miller, who revealed his own sexual manipulation. Lieutenant Benson and Detective Rollins questioned Daniel about his ex-wife. Daniel revealed his thoughts about Nicole's personality, while voicing how she had no sense of self and that he never thought she would destroy her own son.
When Luke nearly waivers, Daniel was concerned about his son possibly going to jail due to the fact that he would be given immunity had he testified against Nicole. However, Benson got Luke to see how he was being manipulated, which allowed him to testify and got Nicole convicted. Afterwards, Daniel walked Luke away from her cries in Luke's direction to take him home. (SVU: "Motherly Love")