Dave Kristler came into the ER after the meth lab he was running exploded.
Dave and his wife were cooking meth when it exploded. Marla and their son, Brian, were injured in the blast and were taken to the ER. Dave was upset because Brian wouldn't stop crying after the explosion. After labs showed that Brian had crystal meth in his system, he had Laura stay with them so he wouldn't be alone with Brian. Callie Torres ordered him to call social services to handle the situation, but he confronted Dave when Dave wondered why Brian wouldn't stop crying, saying he couldn't stop crying because the meth had fried his system. Dave punched Alex and took Brian.
He went and hid in his wife's bathroom and Brian had a stroke. Derek found them and took Brian so he could have surgery. Dave was then arrested for cooking meth.
He is married to Marla Kristler. When he lost his job, they started cooking meth together to make ends meet.
He and his wife have a son, Brian. While they cooked meth, he passively ingested it. After the meth lab exploded, his grandmother came to take him because his parents were arrested.
Marla and Dave are friends with their neighbor, Archie Roche. He sometimes babysat Brian. When he found out that they had been cooking meth, he was shocked and disappointed.
Dave had lost his job, which is why they started making meth.