10 Biggest Unanswered Mysteries In The Simpsons

Grampa Simpson, like Lisa, has never had much luck in his love life. He cheated on Mona before she left him, Bea's untimely death left him heartbroken and alone, and his relationship with Ms. Bouvier didn't last anywhere near as long as he would have liked.

The reason for their break up was Mr. Burns. Homer's boss stuck his extraordinarily long nose into their business and stole Marge's mother away from Abe. However, the two seemed liked total strangers, yet there is no way that they wouldn't have recognised each other given their history together.

Grampa described the man to Homer as 'a repulsive, obnoxious old billionaire', suggesting he didn't know much more about him than that. Yet, two seasons later, their shared past in the Flying Hellfish together was revealed. They fought together in the war, and at the time of their battle over Ms. Bouvier were both entwined in a tontine with each other, a pact for the last man alive to take possession of a stash of priceless paintings.

In 'Raging Abe Simpson and His Grumbling Grandson in 'The Curse of the Flying Hellfish'' in season seven, the two knew each other well enough, and remembered details about each other from all those years ago. However, neither had the mind to either mention the priceless German paintings hanging in the balance, or the fact that they were so well acquainted when fighting for the love of a woman.