Thanks to all, for giving your mental support to my crazy Redguard.
I just got an email back from the Guinness Book people by the way. Turns out there is no such thing as "Longest Period of Time for one Character to finish a Bethesda Questline" dangit.

Joking. Seriously, though, I had no idea it'd take this long to get to wherever he has gotten to, when me and Lopov created our Redguards side by side long ago in September of 2012.
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Sun's Height 10, 3rd Era 434Days Passed: 318
Play Time: 285:38:32 (Please stay away, wicked A-bomber!)

He opens up the door, and finds himself in a large, circular chamber, dominated by a massive, hanging cauldron of fire. The Imperial Library is the exact opposite of the sewers. It was a little too cold in those sewers. Now it's a little too warm. Kahreem feels really glad that he ditched all that heavy armor.
Despite being an inner portion of White Gold Tower, the room is still massive.
Expensive windows of colorful stained glass are spaced evenly between each column of cold stone. Kahreem thinks back to his youth, back to the days when he was touched by the cold hands of the monastery. He'd heard rumors at some point that all of Cyrodiil's chapels are supposedly "showered in gold," but so far he hasn't seen anything of this sort. The Imperial Library comes closest, though. This is definitely the most regal and ostentatious place he's ever been, he thinks. One thing he doesn't see though, are books.
He can hear some bookworms though. Matter of fact, he hears one turning pages somewhere below him. He wonders if this bookworm is a lore-geek, for no particular reason.
"Hmm," he says aloud, the roar of the fire drowning out his voice. It's good to finally say something in a normal tone of voice, he thinks, as long as he does not speak directly to one of the priests. "As the Grey Fox says in his note, I must now go to the bottom floor of this so-called library."
There's a spiral staircase located about forty paces away, if he avoids the two priests rambling slowly on this upper level. All of this goes easily. And once he's down the stairs and in (what he assumes to be) the main bulk of the library, he can't help but laugh aloud at its lack of books. He counts seven bookstands in all, with maybe a total of 50 tomes. He nears a shelf, expecting to find some book he's never heard before.
"Maybe this library is so small because all its books are rare."
This seems not to be the case though.
"Fundamentals of Alchemy? Trials of St. Alessia? History of Lock Picking?"
Nothing out of the ordinary, which means nothing he can steal for extra coin. So instead, he unrolls the scroll given to him by the Grey Fox again, to see what the next step in The Great Heist shall be.
QUOTE
6). I have arranged to have a particular scroll made available in the Chamber. The blind monks that care for the scrolls are expecting Celia Camoran, but you will take her place. Just find the chair assigned to visitors to the library. You must not speak, or they will know it is not her. Just let them bring you the scroll.
Though there are several benches, there is only one chair in the vicinity. Kahreem correctly guesses that this must be the correct chair. He sits down. And notices the 'bookworm' he'd heard before, which happens to be one of the moth priests, one of the
BLIND moth priests.
"By Sithis, how is he able to read if he is blind?"
Kahreem shudders a moment. Maybe he's not blind. Maybe none of them are blind. Maybe he's just walked into some sort of trap! ... They're also expecting a woman named 'Celia,' and he certainly does not smell like a woman named Celia. He smells like a man named Kahreem, who smells pretty much like the last beer he drank.
Is this the end? Have I come to my doom, in this circular joke of a reading room, killed by dozens of monks? ...His worries are for naught, though. Almost on cue, one of the priests he'd seen upstairs begins coming down the spiral staircase. The man pivots right, and then lays a scroll right beside the Redguard's hands.
"Celia Cameron," the priest says. "I present to you the Elder Scroll you requested."

It takes a bit of willpower for Kahreem not to reply in a silly female voice. After the priest lays one of the rarest artifacts in Nirn upon the table, he immediately begins to walk away. Which is good, of course. Kahreem realizes it's time to go, but he can't help but just sit there a moment. He looks within his sack, and finds a second beer. Can't help but crack the cork off its top. Can't help but glug this beer down too, right there in the sacred library.
"I wonder what it says. Ha! I wonder if I'm about to go blind from reading it."
He can't help but open the scroll, which contains a series of runes and esoteric symbols. They mean nothing to Kahreem, and as the second beer takes some effect, making him feel all swimmy once again, he feels a little disappointed that whatever this Elder Scroll says, he cannot even fokkinge read or understand it at all.
"Well hey, at least I'm not blind."
He gets up, and wanders off, hoping he won't have to go all the way back through all those sewers, and such.
^|^|^|^|^|^|^|^|^|^|^|^|^|^|
"Hey, I'd better cut down on the ale," says a female Imperial voice. "Starting to see things, I am."
Kahreem realizes he's gotten up from his chair a little too fast, and does not crouch down after he does so. Instead he stands fully. This causes the bookworm priest to get up suddenly from her bench, and come rushing over. The thief keeps his cool though. Immediately hunkers down, and gets into what little shadow there is.
"Hmm. Whatever it was, it's gone now," says another priest. A male. BOTH moth priests now come down the spiral staircase. One of them raises his fists!
Fokkinge to Molag Bol.The thief wobbles on his feet a moment, really wishing he hadn't downed that last beer! The priests take no further action though. They seem satisfied that nothing foul is going on, and wander off. Kahreem begins the slow process of vacating the library, and all fifty of its books.
QUOTE
7). Once you have the scroll, retrace your steps and deliver it to me. Of course the chances of something going wrong with this plan are very high. When that happens you'll just have to get creative.
"Ha! Yeah! Well I certainly am creative!"
The library exits into one of the outer halls of the Imperial Palace. Again, this hall is circular. It is also quieter out here. No roaring fires to drown out his footsteps. Luckily, there is some magical music playing, but the Redguard must still be careful.
He wanders literally right in front of a palace guard, who just stands there, lost in thought. "Heh, I'd better cut down on the Tamika's," this guard jokes to himself.
Kahreem then comes to a door which says "Imperial Guard Quarters," and easily gets into it with one of his keys. But this part of the Ultimate Heist is not so easy. His initial instinct is to keep moving downward, taking rights as he enters those circular hallways. This ultimately leads though to a door labeled Elder Council Chambers. And this door cannot be opened by any normal key or lockpick. it is only after hours' exploration that he discovers the way out is not down, but up.*
Kahreem's lockpick count falls to just 18, as he opens several locked doors in a row, some of them 4 or 5-tumblers. Of all the keys he's go on his person, it's odd that none of them open these last final doors. But he does find himself in one final bedroom, which has an empty hearth. Oddly, this hearth has what looks to be a grate underneath its empty log-holder. And the grate looks movable. Almost like a door.
"Hmm."
He moves the log-holder aside, and opens the grate. This grate is magical though. As soon as he opens it, he's already falling toward ...
"ARRGH!"
.... a floor, far below the safe, secure Palace Guard Quarters and its empty hearth.
"Fokke that hurt! ... That must been what those boots of Springheel Jak were for!"
The chute he'd fallen down empties into an area he's become well-familiar with though. Back in the sewers. In fact, he even knows which part of the sewers he's now in, since he hears the sound of
this -- ghosts nearby. He also hears plenty of dead-eyed skeletons, and at least one shambling zombie nearby. Nothing Kahreem hasn't dealt with before.
"The trick now is to be methodical. Don't offer myself as bait. Maybe those undead won't try to hack great lumps out of me. Hmm." He stops, and thinks about the sounds of those skeletons, and how even with his heavy dwarven warhammer, it had taken way too long to kill one of these. "One thing's for sure. When I get back to the outside world, I'm going to have to improve my weapon skills."
He drinks nearly all the healing potions he's got, before figuring his way out of the Imperial Sewers, hopefully for the very last time.