The old man in the walker worked in construction. He built this suburb and planted those pine trees on the median of Peacock Hills Estates. One day, it was hot, and he was young and lazy, so he instructed his men to take it easy. They didn't dig through the clay -the caliche- deep enough, only a mere foot or two. And when they planted the tree, it took to the ground okay, but the roots never went deep, they ran shallow. And after about twenty years or so, you could see the rise in the asphalt. Cars would hit it with a goodly WHABUMP, but locals knew instinctively when it was coming, and they would slow appropriately, when their brain sensed the correct amount of drive time elapsed since the last intersection. After the first few times, no one noticed anymore.

Chin had tripped over the rise in the sidewalk slab, and Mike1819 saw her do it and ran to help. She didn't recognize him, in the shirt that he'd grabbed from the debris out front of the FOR SALE house. This is how they became friends. After he cleaned himself up.

Jake was installing fake grass just up the street, and had hit one of those roots and had to dig around it and have it manually removed, one hot day, as he cursed the sun, and the man who planted that tree, who was just passing by in his walker and Jake didn't recognize him.

After Jake cut that root, the tree began to go brown, and he noticed it on his run. The fake grass, and the dying tree, in an ironic reflex, and it bothered him. And later that year, when the Santa Anas came  that October, the tree went down,and the drunk college students coming home late from a party didn't see it, and crashed. While recovering from the hospital, the Dude decided to ask his girlfriend to marry him, and kicked his frat buddies out of the house. 

Then the kid and his girl had a baby, at the same time as Jake and his wife, and the kids maybe became good friends.

Mike1819 is the old man's son. They had a falling out. Araceli Flores asked if she could pray for the old man, since she saw him in the walker. He said No, pray for his son, whom he hasn't spoken with in years, and who lives a mile away. And she did, and he met Chin, and his life was changed.