For a long time, Dutch Wagenbach's only true friend was his former partner, Claudette Wyms. The two have a rather complex and symbiotic relationship: Claudette uses her emphatic touch to counterbalance Dutch's psychological means of solving violent crimes while Dutch is able to keep Claudette grounded emotionally, so as to prevent her from allowing her personal grudges and vendettas keep her from seeing the big picture towards their jobs as detectives.
Though friends, Claudette did share in the criticism of Dutch's ego. Her reaction to this egomania has been a systematic campaign of mean-spirited practical jokes waged against Dutch, including leaving dog manure inside his desk drawer. Dutch has taken upon himself to blame Vic Mackey for the pranks, a charge that Vic refuses to acknowledge or deny because Mackey secretly takes great joy in watching Dutch blame him for all of his problems.
Because of Claudette's unwavering determination to do the right thing, no matter the cost, Dutch has at times paid the price for his loyalty. For a time, Dutch found himself subjected to a blacklisting by the Los Angeles district attorney's office, who made it clear to the LAPD that any criminal case that involved Dutch and his partner Claudette would not be prosecuted. As a result, the two were demoted to working minor criminal cases for over six months before Captain Monica Rawling confronted the DA's office and threatened them into removal of the blacklisting of the two officers. However, Dutch struck a deal with the DA that Claudette subsequently discovered, and there was bad blood between them until the end of Season 4. After Dutch turned down a chance to replace Monica Rawling as Captain of the Barn, he told Claudette that the Chief wanted him "to be the spineless, company man, jellyfish. I told him to shove it."
Since Claudette took over as Captain of the Barn in Season 5, Dutch remains one of the only detectives whose judgment she trusts completely. In Season 6, the two collaborated in proving that Internal Affairs Lieutenant Jon Kavanaugh had planted evidence implicating Vic Mackey in the murder of Lem. She referred to Dutch as "my best detective."
In the penultimate episode of Season 7 both Dutch and Claudette are watching as Mackey confesses his crimes in exchange for immunity. Furious that Mackey had got away with so much, Claudette actually fired Dutch out of frustration as he tried to calm her down. This was shown to have been disregarded soon after when Claudette calmed down. In the final episode Claudette reveals to Dutch that she has stopped taking her lupus treatment as it apparently no longer works, and she's accepted that she's into the terminal stage of her illness.