Why Dawson Really Left Chicago P.D. After Season 6

screenrant.com:

Antonio Dawson is one of the original characters of Chicago PD, so it was totally unexpected when he left the series at the end of season 6. The Chicag0-set police procedural has been on the air for nine years now. While Intelligence has mostly kept its core team, it has also gone through some personnel changes, including the sudden departure of Dawson (Jon Seda) from Hank Voight's (Jason Beghe) team. 

Long before Dawson joined Intelligence, he and Voight already had a history together as he was the one who nabbed his future boss in a bribery sting. As he usually does, Voight was able to get out of prison and, through a deal, was even handed his own department. Despite their less than ideal past, Voight's first hire as Intelligence leader was none other than Dawson. Throughout his stint in the Dick Wolf-produced, Chicago PD, Dawson acted as Voight's second-in-command, taking over the team whenever its Sargeant was occupied with other matters. 

Related: Chicago PD Season 9 Finale Resolves Its Biggest Issue From Season 1

Voight and Dawson cannot be any more different, that's why they worked well together as Intelligence leaders. While Voight has no issues crossing lines and breaking the law if it means serving justice or for the sake of people important to him, Dawson is a stickler for the rules. So, when Dawson was effectively written out of the show in Chicago PD season 6, it was a huge blow to the series' cast dynamic. There was no clear reason given as to why Jon Seda exited the police procedural, but according to a report from Deadline, the decision stemmed from the feeling that the character had run its course. Instead of keeping him in Chicago PD without any fresh ideas on the table, NBC decided to write him out of