Okay, I explored through darkwater pass and to find an imprisoned argonian. He wants me to help him find his way out. yet, he will not follow me. I have tried waiting in and outside of the cave, and he will not respond beside me. I have no followers. talking to him does nothing. What do i do? or is this merely a glitch?

I'm getting a bug with this guy. i break him out, but when i lead him to the exit he wont leave the cave. and if i re-enter he is back in his cell and will not follow me again.. any known fixes?

He won't follow me either.
I got him to the exit by taking just two steps at a time where he would take two steps also and ask "yes?"
But once at the exit he will not follow.

I give up, as far as i'm concerned he can rot in that cave and he's lucky i didn't kill him instead!

Resurrecting this thread, as I am not able to get Derky-boy to follow me out the door, either. Anyone find a way to fix this, yet?

The only fix I've found is to reload a past save and try again.

If you are on PC, "...go outside the cave and use the console and type prid 1B08D and moveto player and then talk to him..."
I have used it and it works.

Source:
http://www.uesp.net/wiki/Skyrim:Derkeethus

there should be 2 exits to that cave , i noticed he will never follow me to one but will follow me to the other exit tho sometimes it takes forever before he actually follows me maybe that helps

The above poster is correct. Do not try to lead him out the way you came in. Continue clearing past the waterfall and exit through the back door to complete the objective and unlock him as a follower.

Thanks, Greywulf. I got him out, because rather than go back to the door I first came in from, I took him with me and we both exited the "front" door together.

EDIT: And I see pms00 had it right as well.