Cornered rat problem

After the thalmer embassy mission when you return to delphine and she tells you about esbern and what to say to him, the quest never opens up,when you go to the flaggin no option is given to ask about him, and if i go to the ratways to the door where hes at he wont let me in .ive went back several saves with the same outcome. any help would be appreciated.

Its weird, I'm going through the same issue.  Delphine tells you to talk to Bjork (thieves guild) he'll want you to do something for him.  After you do it he'll tell you to meet him in the ratways.  This is as far as I've gotten.  When I meet him in the ratways he wants me to do more quest like I'm joining the thieves guild, but I don' t want to with this char.  Maybe it will be different for you.  Try it and let me know what happens when you talk to him at the bar in the ratways.

Same here, I've done all the Thieves Guild quests first intermixed with some other quest (even main quest). Now I wanted to continue the main quest and realized that I never got the Cornered Rat quest form Delphine. Decided to look Esbern up without anyone telling me to (Brynolf won't talk to me any more and Vekel has no quest related questions/answers).

When I knock at the door the hatch opens but immediately closes. Still no quest...

Oh: and I found this bit online: http://www.uesp.net/wiki/Skyrim:A_Cornered_Rat

Bugs: There may be a glitch in which if you are halfway through the thieving guild quests, then you will not be able to continue the quest as there are no dialogue options for Brynjolf. (Xbox 360- No Solution found)

Man this relly sucks.  So your saying that even if I do all the thieves guilds quest (which I don't want to do with the char) I will not be able to complete the main quest.  That sucks.  My mage is lvl 51 and I wanted to do a straight mage char and beat the game with her.

Pretty much yes. I wanted to sneak through the main quest line as much as possible. That's why I started off with the Thieves guild quest line and choose to be a Kahjiit. So I'll clean up as much as I can in this run and perhaps start anew and only do the main quests later. Also hoping that they DO fix it. I must admit that this is the first time I've come across such a major flaw in an RPG so far.