In the last episode of Supernatural Season 10, Dean summons Death to kill him, so that he will not be turned into Demon due to Mark. However, Death tells him that he cannot kill Dean with Mark as it will free the 'Darkness'. However, he can send Dean far away and Dean needs to kill Sam  , so that Sam will not try to bring him back.

However, he changes his mind at last moment and kills Death instead of Sam. But why kill Death, he can simply leave Sam.

In the last episode of Supernatural Season 10, Dean summons Death to kill him, so that he will not be turned into Demon due to Mark. However, Death tells him that he cannot kill Dean with Mark as it will free the 'Darkness'. However, he can send Dean far away and Dean needs to kill Sam, so that Sam will not try to bring him back.

However, he changes his mind at last moment and kills Death instead of Sam. But why kill Death, he can simply leave Sam.

In the last episode of Supernatural Season 10, Dean summons Death to kill him, so that he will not be turned into Demon due to Mark. However, Death tells him that he cannot kill Dean with Mark as it will free the 'Darkness'. However, he can send Dean far away and Dean needs to kill Sam , so that Sam will not try to bring him back. However, he changes his mind at last moment and kills Death instead of Sam. But why kill Death, he can simply leave Sam.

In the last episode of Supernatural Season 10, Dean summons Death to kill him, so that he will not be turned into Demon due to Mark. However, Death tells him that he cannot kill Dean with Mark as it will free the 'Darkness'. However, he can send Dean far away and Dean needs to kill Sam , so that Sam will not try to bring him back.

However, he changes his mind at last moment and kills Death instead of Sam. But why kill Death, he can simply leave Sam.