My Pumpkin Witch

I'm Marnie, a witch who owes the Bureau of Supernatural Affairs $250K. They sent a deadpan necromancer as my partner. He knows my herbs, my habits, calls me "Pumpkin", yet I don't know him. Then our hands touched. I saw an ancient memory: a man in dark robe smiling at me beyond a barrier. Who is he? Who am I? If I remember, can we still fight?