Fox's sci-fi drama Fringe — sort of an X-Files with a parallel universe instead of aliens — started off tentatively but blossomed in 2010 as it embraced its weirdness. This pivotal flashback episode fleshed out its mythology, explaining how Walter Bishop (John Noble) did the research that breached the wall between parallel worlds. More important, it deepened the emotional backstory, showing Walter's pained decision, decades ago, to abduct the parallel-universe doppelgänger of his son Peter (Joshua Jackson) after he died of a childhood illness. In a masterly performance, Noble makes the hubris of the younger Walter and the regret of the elder Walter achingly real. (Fox)