Fridge Logic: Almanzo tells Laura that his sister, who's been the schoolteacher for several months, often spoke of her. Eliza Jane Wilder hated Laura, believing her to be the one instigating all the bad behavior in the other children, so odds were she wasn't saying anything terribly complimentary. So what does Almanzo go and do? Start courting her, even if Laura didn't figure it out right away. It leaves one wondering just what Eliza Jane actually said, and how much it might have contributed to her brother's decision to court Laura, who was at the time only fifteen.
Fridge Brilliance: Sibling rivalry. Farmer Boy shows that Almanzo and Eliza Jane didn't really get along, and the years probably didn't improve on that much. He could have started meeting Laura just to antagonize Eliza Jane, and then genuinely fell in love with Laura.
Considering that Almanzo's comment comes after a whole string of incidents including the seat-rocking episode described on the Crowning Moment of Awesome tab, he may even have been able to see through Eliza Jane's dislike enough to be impressed by Laura's sheer audacity.
Fridge Horror: Do NOT get Laura angry with you. Cases in point? She refuses to pray for her brother. He drops dead. She complains about having to take care of Jack (their dog). He drops dead. She gets into a romantic rivalry with her sister, Mary, over a neighborhood boy. The neighbor boy prefers Mary. Mary goes blind.
Ben Woodworth's father came to North Dakota to take the "prairie cure" for his tuberculosis, and seems to have recovered. There wouldn't be an actual cure until the 1950's, and tuberculosis is extremely contagious, so who knows how many people he managed to infect without realizing it.