Samwitch
Samwitch is a portmanteau name for fanfiction pairing the characters Sam Winchester and Rowena in a romantic or sexual relationship.
The pairing was sparked after Sam sought Rowena's help in decoding the Book of the Damned.[1][2][3] Years later, when Rowena resurrected herself after being killed by Lucifer, she and Sam form a bond over their shared torture at his hands.[4] Before Sam kills her, Rowena views Sam as her protégé in magic, and notes that they've grown quite fond of each other over the years.[5]
The name enters canon in 15.13 Destiny's Child, when Dean calls Sam "Samwitch" after Sam offers to perform a spell in order to transport them to Hell and back, although he is using it to refer to Sam's proficiency with magic, rather than his relationship with Rowena.