I've been reading ouroboros and have been looking for somethin similar.
But as Harry is tortured he somehow manages to get some revenge either during or after escape. Like he loves it so much he turns into a cenobite. Lol, crossovers or pure HP don't mind.

 

Lies that Bind by Zephros.

It's not amazing, but its also not bad.

Don't know why you want that sort of thing though.

 

Not a tortured Harry fic, but does have imprisonment and revenge :Escape to Darkness by kmfrank

It's an ok fic. I think the writing gets better through the story. WIP.

Also, if you into that kind of thing for stuff outside of fanfiction as well, Old Boy is a pretty popular movie you might want to check out.

 

Heh. I was just talking about Ruskbyte's From the Abyss with Klael on IRC. It's not complete, and probably never going to be, and is only 5 chapters long, but when I read it, I found it to be awesome.

 

http://www.fanfiction.net/s/2070225/1/

Not a bad story. I rather enjoyed it myself. It's a captured/tortured Harry. Though the story might not be up to DLP stanards.

 

Found this yesterday. Features captured and tortured Harry. No revenge part, though. Written by Zennith last year, and surprisingly without any review yet.

PS: The scenes are horrific and disturbing. I enjoyed it a great deal.

 

Holy crap. I forgot I wrote that thing. Yeah, I don't know if I'd suggest reading it. I think I was trying to gross people out? Or maybe just be fucked up. Who knows.