Disclaimer: I do not own Grey's Anatomy.
Meredith loved her nephew. He was adorable. Lexie? Not so much. Within a week of Michael being born, it was evident that Lexie was struggling in her new role. She cried constantly, and had even kicked Mark out one night for seemingly no reason.
Meredith knew that Mark was worried too. Michael was now a month old, and Lexie was becoming more withdrawn by the day.
Even Thatcher was concerned. Meredith had spoken more to her father in the month since Michael was born than she had in the last several years.
But the night Lexie didn't come home from the grocery store was the most terrifying. Mark had just returned from seeing Sofia when Lexie had all but shoved Michael into his arms and walked out the front door, saying she'd be back later.
At the time, he had just assumed that she needed a break and was making a quick run to the store. When she hadn't returned after three hours, he had started panicking. At four hours, Meredith had called the police. At five hours, Derek had rushed back to the hospital to see if the Jane Doe brought into the ER after a car accident was Lexie.
It was only after 7 hours that Lexie had been found by Thatcher when he had returned home from an AA meeting. She was laying on the bed in her childhood room, in the pitch dark, sobbing.
After calling Meredith to inform her that Lexie was alright, Thatcher spent the rest of the night holding his daughter as she cried herself to sleep. Molly had been on the first flight to Seattle the next morning.
If it hadn't been clear to Mark before that Michael was a momma's boy, it definitely was after he spent the night caring for Michael on his own.
When Lexie finally came home, she was escorted by both Molly and Thatcher, as though without them she would attempt to flee. When she walked through the door, Mark was standing there silently, holding Michael.
Lexie didn't even look at them as she went upstairs, not to her room, but to the attic, locking the door behind her.
Not even the sound of her son crying for his mother was enough to get Lexie to open the door. She simply laid on the now bare mattress in the attic, staring at the wall.