John Clark writes: Celebrities generally come in two sizes: large and small. Either they suck up all the oxygen in the room or you can’t imagine how they take up so much space on the screen. Viggo Mortensen somehow occupies a middle ground. He’s dressed down for an interview, looking at ease in a blue soccer shirt and blue jeans, but at the same time it’s easy to imagine him wielding a sword (the “Lord of the Rings” trilogy), a lethally hot pot of coffee (“A History of Violence”) or a pair of sinister sunglasses (“Eastern Promises”). Which is what makes Mortensen’s newest film, Vicente Amorim’s “Good,” such a change of pace. Based on the play by C.P. Taylor, it’s about a literature professor in 1930s Germany (Mortensen) who allows his academic work to be co-opted by the Nazi government. He soon follows suit, abandoning his wife and family for a younger woman, donning the uniform and allowing a Jewish friend to be swept away. Things are getting ‘Good’ for Mortensen