There’s a pattern. A pattern behind death of most of the major characters.
- Remember this scene from Season 1, Episode 1. Ned beheaded the deserter.

He later gets beheaded by his own sword.

- Tywin Lannister ordered the deaths of Northern Lords via crossbows.
He later gets executed by Tyrion, using crossbows.


- In the Red Wedding, Roose Bolton drives a dagger through Robb Starks’s heart.

Surprise!!!

- Catelyn Stark’s throat was slit on Walder Frey’s order.

Later,

- Ramsay liked to feed people to his dogs.
HoHoHooo!!

- Jon Stabs Qhorin Halfhand.

He is stabbed by Night’s Watch Brothers.

- Olenna used poision to kill Joffrey in Purple Wedding.

She is poisoned by Jamie, later.

- Little Finger puts a dagger on Ned’s throat.

Arya Stark kills Littlefinger, using the same dagger.

source:QuoraKarma struck them hard.