Her father Kevin met her mother while giving a lecture on reading body language at a university. Her mother was impressed with his charisma and charm, they talked afterwards. This came to that, then going to a bar, and basically, Lynn is the product of a drunken one-night stand. Lynn was delivered to her father in a golden cradle, delivered by the West Wind. Her father was so shocked, but fawned over the baby girl. He found a card under Lynn's blanket. It read, "Lynn Conners. Smile."'
Lynn grew up happily with her father until she was eight. They were coming home from a night at the movies, when Kevin was confronted by two men, who robbed, and shot him. They ran off, not even noting Lynn, because she was so small and quiet. Lynn began to cry over him, and Kevin put a hand on her cheek. "Smile, Lynn. Promise me you'll smile." Lynn was freaking out at this point, so she just nodded rapidly and Kevin died on the street. Someone had called 911, so Lynn ended up get dragged away from her father's body by the police. She was interviewed, then placed into foster care.
She drifted from house to house afterwards. one foster home locked her in a closet, other gave her nothing but dog food to eat. All the while, she just kept smiling, even when tears came, she was always smiling.
A few years passed and when Lynn was 13, a monster first took notice of her. She was at the park after school, avoiding going home, when she got a strange feeling. She got up from the bench and looked around, finally spotting what was giving her chills. It was a man in a coat. He looked like he was made of mist, but his eyes were bright red, and he had fangs.
It was Mormo, a spirit from Hecate who bit bad children (according to legend). Lynn grabbed her bag off of the bench she was sitting on a sprinted away from the park. She found a Satyr that day by accident, or maybe fate. Lynn had hopped the fence and ran into the woods near the park, and she ran (literally) into a Satyr, who was taking another half blood to camp. The Satyr (whose name was Terrence) could tell she was a half blood (by smell) and tried to take the both of them to camp.
Mormo followed them, and just before reaching camp, they were attacked. Lynn freaked out once more and panicked, but the other half blood and Terrence fought Mormo, until Mormo was sent to Tartarus. The other half blood was injured, badly. He later died of his wounds at the Big House. Lynn blamed herself for his death, and Terrence could see it. They ended up having an Iris message with the half blood who died and Lynn made peace with him, knowing that he was in Elysium. Lynn is sometimes (sarcastically) called "Sunshine Girl" because she is always smiling and cheery.