David By SARA VANDEN BERGE   One of this week’s featured pets up for adoption at the Erath County Humane Society is David, a five to six-year-old domestic shorthair with a big personality.   “This sweet boy came to the shelter after his owner sadly passed away, but he hasn't let that dull his friendly spirit,” ECHS executive director Serena Wright told Beneath the Surface News .     “Walk past his kennel and he'll likely reach out with a paw to snag your attention. He loves