heres the deal: id would love questline where you console the grieving jarl (and ive never modded in my life), say that her husbands remains for starters were taken by necromancers and they played all their hocus pocus into making him into a lich/draugh (one whos a competent magic and sword wielder) and they are using him to terrorize the country side in revenge for their foiled plans for potema.
since hes so powerfull you cant face him directly or youl get owned, so youl have to choose beetwen 2 quests, one diminishes his magic capabillities, the other drains his strenght away

also you will learn that the necromancers placed a clever spell that if one does not kill him without a special soul gem in their possesion, if you do his soul will transfer to your body and the cycle begins anew.
now wouldt want to make things easy so they broke this gem into 3 pieces and stashed them in diffrent locations, one in a grave hall so the power of the dead is still fueling it, one in the hands of a hagraven they formed an alliance with in order to strenghten the spell on the late king, and one was given to a thalmor mage who has sympatetic wies towards their branch of magic and is secretly funding them. now the first two is just hack and slash get the gems then get out, the thalmor is to heavily guarded not to mention diplomaticly immune, so you will have to sway him by a) bringing him a dwemer cog from the last guardian (imagining a dragonsized killer robot with a temper to boot...and a massive electro shock attack to make things intresting ) the focus of julianos, a gem found in a wreck out in the ocean...only thing in the way is a gigantic slaugherfish you cannot kill, so youl have to play hide and seek or c) youl have to empty the treasury in the empire castle dour...without being noticed at all (and all that treasure is heavy, youl need to sneak in several times with ever increasing security).

Optinal quest: the thalmor will be so trhilled by wichever the item you bring him that hel give you a tip: one of his seniores and a fierce rival of him is carrying around on a amulet that drinks a portion of hostile magic and flings it back at the attacker, he is currently investigating a hidden cult of talos worshippers and he wouldt be sorry to see him dead (wink wink) now they are holed up in what appears to be a cave but further inside the clever nords have hewn out an underground chatedral for telos, and there is a fierce battle going on, you can choose sides here, helping the thalmor in hopes of getting their leader in a secluded spot, or help the nords who wants to defend their faith, the choice is yours

now that you have your choosen path you defeat the king only to find out that his soul was in all secret linked with a second soul gem should all this aspire and youl need to track it back to the necromancers stronghold (using that pathfinderspell thing that shows you the way during questing, oh and not in a durn grave hall pls make a black ominous tower with you know bodies hangin on spikes, the doors framed with human skulls, blood canols leading to an altar on the floor thats glowing red, pillars made of bone....thats MOVING! you know all the tings neccesary to make a cosy necromancer tower) here you will find a bunch of pissed off necromancers working on the kings corpse, leading them will be the skeletal remains of dun dun dun mannimarko tho hes no longer powerfull he can still give advice to the necromaners of the world so you kill off the necromancers and turn to break mannimarcos bones to dust, only to find a barrier in beetwen you and him behind you however the king is finnaly free of his bonds and comes to the rescue, he breaks the seal and you are home free to smack the king of worms.
after this you will dialouge with the king, he says its time for him to move on and thanks you for saving his soul, he also pleads you to take care of his wife and gives you his signet ring, you return to castle solitude, give her the news, and in turn she will say that shes secretly been in love with you since she laid her eyes on you,you can ask to you know hint hint marry her and shel say yes, making you a jarl (and possebly the high king if you play your cards right eh? ) or you can say no, shel get stung and youl get a hefty purse for your job (though you broke her hearth you bastard! ^^).