FAIRFIELD-SUISUN, CALIFORNIA Haijun Si stands in front of his home as neighbors form a nightly security detail to deter teens who have harassed his family by throwing rocks and yelling racial slurs. (Gina Ferazzi/Los Angeles Times/TNS) An Asian American family was being harassed. Now their neighbors stand guard LOS ANGELES — Every night, the neighbors converge on the Si family’s two-story home, which has large windows and an expansive porch adorned with columns. Some sit in camping chairs in front of the driveway. Others keep watch from their cars or patrol the nearby parks. The Sis moved to this upscale Ladera Ranch neighborhood a few months ago, with the country deep in the Covid-19 pandemic and hate crimes against Asian Americans on the rise.