Twix, a tiny two-tone chi with big brown eyes and a mind-boggling ear span, is a cosmic brain teaser. How, you might wonder, does an elderly 5-pound stray emerge from unknowable misfortune with what can only be described as irrepressible gladness? She walks on sunshine, this one, kissing other dogs and people, wagging her way into laps, sniff-a-thons, group hugs, and the future. Sounds corny, but her joy is infectious and her energy is balm for the soul. We think Twix is something special. You?