Sirius the secret keeper
I'm looking for a fic where Sirius is captured by death eaters, and someone uses Polyjuice potion to make Sirius think Remus is being tortured and maybe eventually killed. Remus comes to rescue him, and Sirius says not him, anyone but him. Remus has to convince Sirius he's the real person, and they escape. Also, any other stories where Sirius remains the secret keeper or Sirius or Remus are captured and tortured for info about James/Lily or the order would be awesome too. I've read the Unbroken universe by robin4.