Well, we did it for the best, now its time to do it for the worst.

Lanisters:

If you've seen Game of Thrones, then you should know the spoiler behind this one.

The Ottomans:
Whenever a Sultan Died, the male heirs would basically go HungerGames and kill the shit out of each other to have only one heir.

Kane and Abel:
Does it mean something that the first murder was one guy who killed his brother?

Jax Teller and Trinity Ashby:

Little SOA spoilers ahead, But John Teller had a Son named Jax. While John was working with the IRA he had an affair with one of the heads of the IRA's sister and had a whole other girl named Trinity that nobody else knew about. Flash Forward 30 years, and when Jax is in Ireland to save his son from the peasant who kidnapped him in the end of season 2, Jax gets turned on by that Irish Butt and is about to get down and dirty when the mom walks in and has to break the news that they are half siblings.