[quote=@MiddleEarthRoze]
In terms of the sex, I would agree with Pirouette on that matter. After all, killing for him would be a form of passion; it would then make sense for him to partake in other forms of passion, such as debauchery. Not only that, but to force someone into celibacy and then make them retain that for the rest of their life - without your influence on them - Would be pretty much impossible. It is a carnal, physical thing that you can't evolve someone out of - so the sex - and rape - I do agree with.
However, in terms of him leaving the Dark Brotherhood, I doubt he would just be allowed to leave. A more likely thing to occur would be that he was presumed dead by the last member of the last DB sanctuary in Cyrodiil (Bravil, I think it was) - ergo, Cicero. With the rest of the group definitely dead, and Cicero definitely assuming that Tyrion was dead, that would make him dead in the eyes of the last santctuary. Also, what with the Dark Brotherhood falling, that could give him cause to leave. If he's the 'perfect assassin', he'd be able to work out when his group was going under.
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It's not as simple as that, they can always detect and determine where their members are, as many Instances both in Skyrim and Oblivion have determined.
Their pact with Sithis and the night mother is eternal up until expiration of life, and Sithis, as well as the spectre of him would likely not wane, he is not like the Dawdric princes where the strength of the DB matches his own, he simply is, as well as this he doesn't prevent the dissolution of the DB, even though the Skyrim faction is remaining strong, irregardless of Ciceros plans; if the listener ever arises that is.
Sithis will still punish his own when they disobey, and whilst there is no evidence to suggest that the wraith if Sithis is aligned to him, even though it's name should suggest that it is, there is no proof to disprove that fact either.

In the end, I recommend that the Bio be modified to a more agreeable basis, one can be an assassian that is unaligned to the DB and still be as equally efficient, the Morang Tong are a perfect example, although, I do believe that one must be a Dunmer to be apart of that, I'm unsure of the specifics.