Nicole Severide grew up with her older brother Kelly as one of the only people she could trust. Then she started work as a paramedic on Ambulance 61. She rose through the ranks to Paramedic-in-Charge and started dating Lieutenant Matthew Casey of Truck 81. (Seasons 1-7) SeverideXOC!sister CaseyXOC Paramedic!OC Part 2- Family Fire