He says that they could give Siegfried a potion ( a special drink ) which would make him forget that he loved BrÃ 1\/4 nnhilde . He reminds Gutrune that he has given her a potion that she can use to make Siegfried forget BrÃ 1\/4 nnhilde and fall in love with Gutrune ; under its influence , Siegfried will get BrÃ 1\/4 nnhilde for Gunther .