In chapter 18 in the book lyddie what is her reaction to Luke's letter why

Lyddie went downstairs into the living room and saw Charlie standing there. She couldn't believe it. She just stood and looked at him and then he said "Sister". Lyddie said "Yes, so you've come".

Charlie told her, "I took the railroad car".

Charlie seemed proud of himself and excited that he had taken the railroad. He smiled, but Lyddie didn't recgonize his smile. He was the same boy, but somehow she felt like she didn't even know him anymore because it had been so long.