Situation 1: My character is a good guy yet I wish to do the Dark Brotherhood line.
Solution A: Your character is undercover disbanding the DB.
Solution B: Your character has reasoned that if he overtakes the DB and simply doesnt do his listeners duty. Then no more people will die.
Solution C: Your character comes out of the shivering isles with a warped mind.
Situation 2: I use Alchemy more than any other skill, yet do not want it as a major.
Solution: Your character doesn't really understand alchemy he just puts things in the apparatuses and hopes for the best, as opposed to a scholar.
Situation 3: I dont want to do the Main Quest right away
Solution A: Your character doesnt trust the Emperor.
Solution B: Your character feels he needs more training before he can venture off into oblivion
and so on... This is a thread I will work further on expanding over time if people take interest, but thats the idea of it. Contribute/Comment as you like.