Paramedic (Ambulance 61)
Kelly Severide (Best Friend)
Leslie is a self-confessed lesbian, something that Peter Mills discovers on his first day when the other firefighters trick him to ask Shay on a date.
Shay and Dawson are involved in a serious motor vehicle accident, when oncoming traffic collide with the rear end of the stationary ambulance, this put Leslie in the hospital for a few days, with head injuries but was soon cleared and approved for duty.
Leslie and Severide were room mates and best friends. When Kelly injures his shoulder, she tries to help him by giving him medication and bugging him to go to a doctor, this began to break their friendship to the point were Shay threatened to move out.
The pair have a strong bond and manage to stay good friends, Shay even asks Severide to be the father of her baby because she could not find a suitable sperm donor.
Kelly says himself and Shay would probably be in a relationship if she wasn't a lesbian, it is also suspected that Shay harbours a slight attraction to Severide.
Dawson was the paramedic-in-charge and fellow paramedic with Leslie, they are often seen together and have experienced many moments together, such as the ambulance collision.
They are very close together and they comfort each other in many ways, a testament to their strong friendship.
Death of Leslie Shay
In reference to the episode: "Real Never Waits".
Wallace Boden wedding ceremony is interrupted when Fire House 51 is called to a building fire. Shay and Dawson follow Rescue Squad 3 into the building, they find an injured male and begin administering care. Moments after they switch places, a large explosion occurs, injuring Shay and killing her immediately.