Disclaimer: The characters and stuff don't belong to me. The Quote is from Half-Blood Prince chapter six.
IGOR KARKAROFF
Night was falling and Igor rummaged into his bag. It was a small backpack which was easy to carry and enabled him to move quickly and efficiently with it. He found what he was looking for, carefully he extracted a little bottle with a few millilitres of brow liquid at its bottom and he drank it all.
He extracted his little mirror and watched himself in it transform into a short balding man with blonde beard. Igor always favoured beards. Whenever he chose a person to kill and steal his appearance he preferred a man with a beard, at least he wanted to look dignified.
This one he had met in a bar when he had the appearance of a Mexican Muggle with a thick moustache. Igor invited him to a couple of drinks which he magically filled, not having money to pay for it, and waited until he was drowsy enough to use an Imperius Curse and take him out of the bar into a back alley. There he plucked some hairs out of his beard and ordered him to jump off the nearest roof.
He had enough hairs but was out of potion and out of ingredients. He had to take his occasional trip to his warehouse to collect more Polyjuice Potion. Igor had a system. He kept moving houses and travelling, but he couldn't carry all his ingredients around with him so he chose a permanent building to store his ingredients, cauldrons, prepared potion and some gold.
He Apparated at his warehouse and proceeded to unlock the protective charms to enter, he was short of time having only an hour of potion so he hurried and decided to make it quickly.
He descended the stairs and that is when he noticed something was moving. He twisted on his feet and looked up the staircase raising his wand on the turn. He stumbled and almost fell backwards; this body was new and he didn't completely control it.
After standing there for a few seconds he decided it was paranoia; since Voldemort was out on the open he had been growing more and more mistrustful with every little thing.
In an instant he was proven wrong as a plank of the roof hit the floor. This wasn't normal. Two masked figures stood at the top of the stair, one with the wand raised at the plank, the other towards Igor and had already shouted:
"Expelliarmus!"
He was beyond any hope.
"Well I had thought higher of you, Igor!" said the one that disarmed as he descended the staircase towards the cowering body of Igor Karkaroff closely followed by the other "Knowing the Dark Lord is after you and leaving the protection charms open. Not that it would have mattered, had you placed them; merely you would have gained a few more minutes of your worthless life."
"How did you..?" Stuttered Igor
"Oh, simply observing a bit. How different people arrived at this heavily protected place, stayed a few minutes and left. How these people were found dead some time later and the characteristic that they were bearded."
Igor looked down
"Look up!" said the other Death Eater and removed his mask. Igor remained transfixed as the face under the mask was the same as Igor's current appearance."
"And the trap set by a faithful Death Eater" said the still masked Death Eater "Getting lazy Igor? You should have killed him yourself rather that trust your Imperius curse to throw him of the roof. Or maybe it's a sense of security that you are getting after deluding capture for a year; the same feeling that made you forget to replace the charms today?
"The reason you aren't dead yet is because the Dark Lord had other plans in the meanwhile"
"Crucio" he said and laughed at him twist in pain.
"Like it?" he asked "It's nowhere compared to what you did to me!"
Igor looked at him again
"What? still don't recognise me?" The Death Eater said, his voice angering "How many have you sent to Azkaban, you traitor! CRUCIO!"
He removed his mask and Igor recognised the sunken face of Augustus Rookwood.
"Augustus!" he said "My friend, I am sorry for what I did. I have seen the error, my mistakes. I…"
"SILENCIO!" Rookwood shouted " I DON'T WANT YOU SNIVELLING LIKE YOU DID IN THE MINISTRY WHEN YOU SOLD ME!"
The other Death Eater made a movement indicating him to lower the sound.
"The Dark Lord has given me the honour if disposing of you, to obtain my revenge and his revenge for I am the one who you sold that would have been of greater use to the Dark Lord in his plans because I had the knowledge that He needed and without the which he has wasted his valuable time on Malfoy's advice."
A green flash of light came his way, Karkaroff had reached for his wand and attacked but Rookwood ducked just in time as the Curse was weaker due to being nonverbal because of the Silencing Charm.
"EXPELLIARMUS!" yelled the other Death Eater and Igor's wand flew again, this time into the disarmer's hands.
"Crucio!" Shouted Rookwood
"Crucio!" repeated the other Death Eater as they took turns to torture the traitor.
Rookwood removed the Silencing Charm.
"Kill me!" Igor pleaded
"Not until the potion wears off!" Rookwood explained "I want to see the terror in your eyes."
They continued torturing him for the remaining of the hour until he retook his own façade.
"Now I want you to beg for my mercy!"
"Karkaroff looked at him unable to move after the Cruciatus Curses.
"Imperio!" casted Rookwood
Igor crawled in clear pain and kissed Rookwood's feet
"Finish him off, were taking too long" said the other Death Eater who had remained patiently behind
"True. That's Enough." He agreed
"Look at me" he ordered Igor who obeyed under the Imperius. "Avada Kedavra!"
and a flash of green light rushed towards Igor and threw him further along the floor where he lay dead.
"Lets go" Rookwood ordered and climbed the stairs, left the shack and disapparated.
The other Death Eater followed
"Morsmordre" he enchanted and disapparated. The Dark Mark rose into the air marking the shack as a place were the Death Eaters had killed.
"They've found Igor Karkaroff's body in a shack up north. The Dark Mark has been set over it- well, frankly I'm surprised he stayed alive for even a year after deserting the Death Easters"- Remus Lupin