Hard Time

O'brien is captured by aliens and sentenced to have 20 years of memories from a prison term implanted into his brain.

He copes poorly, losing his temper with friends and family.

We later learn that, in this 20 year prison term, he killed his cellmate for the tiny bit of food he'd been saving.

The "Ghost " of this dead cellmate haunts O'Brien.

Racked with guilt, O'Brien is about to commit suicide with a phaser when Dr Bashir finds him, and O'brien tells him why he wants to die.

Bashir talks him out of it.

He prescribes medication for O'Brien, to help ease the pain and guilt, to be taken only for a while.

Unlike most Trek shows, O'Brien's memories are permanent.

Although he never mentions it again.

But the problem.. the memories... will never be removed.

"I offer you a Vulcan prayer, Mr Suder. May your

death bring you the peace you never found in

life." - Tuvok.