Robert Sullivan is a former battalion chief and current lieutenant at Station 19.

He used to head the house, but when he battled an addiction issue after an injury, it jeopardized his job and caused him to get demoted.

He and Andy used to date and got married, but their marriage fell apart for a plethora of reasons and they eventually got divorced.

And he found love again with Natasha Ross, the current chief and a woman from his past of whom he served with in the army.

After doing shady things to get promoted or his way, he often has a tumultuous relationship with may people in the house, particularly Maya Bishop.