Sir Marcus MacRannoch and his wife, Lady Annabelle, live near Wentworth Prison. MacRannoch recovers Claire after she kills one wolf and is stalked by a pack of more. If Claire is a Snow White lost in the woods, he's the huntsman who saves her. And then he ends up helping Claire save Jamie from Wentworth and nursing him back to health, too.
MacRannoch seems to exist to show us that Scotland is a pretty small place after all. He knew Jamie's mother, Ellen, and even gave her the jewelry that Jamie gave to Claire. While Jamie is recovering at the Abbey, MacRannoch sends Jamie the bracelet to match the pearl necklace. Good karma comes around, we guess, and so does good jewelry.