Bring a pot of salted water to boil. Add orzo and cook until al dente, stirring occasionally.
Meanwhile, melt a pat of butter in a sauté pan over medium-low heat; add red peppers and scallions and cook until soft and fragrant.
Add crab and cook until heated through. Add orzo, lime juice, crème fraîche, and a ladle of pasta water and stir to combine, adding more lime, crème fraîche, and pasta water if desired. Can be served warm or cold.