Have you ever had that kind of character, which, at first seems just bitter at the world, but no worse than any other person, or not even bitter at all, but in love with it instead, yet as his/her life progresses, bitterness begins to pour out, or envy or fear, and the weight of the sword shifts from mostly bearing on the back to being ever-present on the hands, and the corpses surrounding her are no longer just those of bandits, but of those who fight for him/her, only to be behead along with their enemies?

Anyway, Ewe, who I thought would never join the DB, has just not only beheaded Rufio without uttering a word, but the inn-owner and old-woman who frequented the place too.

Any similar stories?

As a rather naive orphan, Buffy was almost drawn in by the lure of a 'loving family'. She stepped back from the brink however and aborted the Rufio thing. Her killing and vengeance, when triggered by her doctrine, are not for hire.

It is our choices that define us.

That Dark Brotherhood intro actually does this pretty well. You slay someone in cold blood (though occasionally the game can be a bit ramshackle with its definition of "cold-blood"), and are offered a step down a path of darkness with the promise of love, wealth, and power. Do you accept the Black Hand, or do you pull back and retain conscience?

Or do you take the middle ground as someone who needs no friends or family and tear his guts out where he stands?

Great opportunity for roleplaying there. Shame there weren't more.

When you hold that blade in your hand, you hold the power to end someone's life. Every choice you make has consequences, but it is up to you to make those consequences end in your favor. The rewards for killing people are great, but it leaves little room for friendship and love, for isn't everyone within Sithis' grasp? One day you might find yourself being contracted to murder your best friend. Can you live with that knowledge and still be an effective assassin? If so, you would go far in the Dark Brotherhood.

My assassin character has no compassion for the weak. Why should she stick her neck out for those who give little in return? She has found that the DB actually rewards her for difficult, life threatening work.

For my character, joining the Dark Brotherhood was nearly happenstance. As others have noted, "Killing in cold blood" can happen in a surprising number of ways.
It was my first playthrough when Lucien came to me, and I was immediately intrigued, moreso than by any other quest in the game. Naturally I did as he asked so I could learn more. When I finally entered the Brotherhood's safehouse and met everyone there, I knew my character had found his place.

For my character, it's about the science of assassination, the craft. There is no emotion involved. I like the alchemy, the stealth, gaining access to places that people are trying very hard to keep you from. In short, it's about the thrill of pulling off a well-planned job. Just running around whacking things with a sword or torching them with uber-fireballs is so dull to me.

For Riden, who is a devout follower and assassin for Nocturnal, is torn when confronted with Lucien Lachance. He isn't an evil assassin. He exists to help those who truly need it and to liberate people from any type of oppression, whether it be religious(Nine Divine zealots) or corruption(Cheydinhal problem) or just regular oppression by anybody against anybody.

So he's still torn, unable to make a decision. He's an assassin for Nocturnal but the Dark Brotherhood is enticing, especially for Riden, who lost ONE HUNDRED THOUSAND gold from buying a castle for his fellow assassins/liberators to reside in. Riden needs money and despite being Nocturnal's champion, there's not much Riden can do to get money.

For my Dunmer assassin, Murtis (born as Fadril Dredayne, but he changed his name after his first promotion in the DB), the Dark Brotherhood served as a rebirth. He considers his first murder and induction into the DB when he truly started living. His life before that was dull and meaningless; he just went through the motions. At three years old his parents were murdered before his eyes, and the Imperial woman who assumed his care gradually began to hate the very sight of him. It eventually came to a point that she denied him proper food and beat him incessantly. He left that household at 13 years old and moved to Chorrol, using what little knowledge he had of alchemy and his love of flowers (even though he is a cold-hearted killer, he's always appreciated the beauty of flowers, and still does) to make and sell basic potions to the local merchants and alchemists.

He was a sad, bitter individual, who often wished that the murderers who axed his parents would've had the stones to give him a whack too. And then, years later after living a life of solitude and despair, he had a brilliant idea. "I'll kill her", he thought. He decided to murder his old Imperial caretaker, and made a journey back to his old home in the Waterfront where she now lived and he was raised. In the dead of night, he broke into the little shack, woke the woman up, looked her in the eyes until she knew who she was staring at, all these years later, and then promptly fed his dagger with her blood. A euphoria overtook him, it was a feeling like no other. He exited and found a beggar staring in his direction: a witness. He'd seen the beggar in his childhood, never knew his name. Murtis's dagger drank twice that night.

A few days later Lucien came to him, and he accepted the invitation eagerly. He finally had a family, finally belonged to somebody, and could live a life of grandeur. See the world, go on adventures, and work as a respected and feared assassin. He instantly loved his dark Brothers and Sisters, and was fiercely loyal to Sithis and the Night Mother. The Cheydinhal Sanctuary was his new home.

When the time came that Lucien gave him the task of Purification, he struggled with it at first, trying to make sense of it. But after some deliberation and careful thought, he realized that this is what it meant to be a member of the Dark Brotherhood and a servant of Sithis. He carried out his assignment smiling.

I always role play the hero that saves the day but then has a moment where he/she turns for lack of a better term, to the dark side.

Very interesting OP, Undreamt.

I think I know what you mean. My so-called ninja, Olaf, was going to be a shadow walker, from the onset, but I did not intend for him to join the DB. Indeed, my plan for Olaf was for him to NOT join the DB. Rather, I saw him as more of a D&D-style thief character (stick to shadows, surprise monsters and bad guys, pick locks, etc.). But as time when on it became clear Olaf had plans of his own. He's become almost the polar opposite of my other main character, Maia (who is Divine Crusader of the KotN and about as justice-serving as any character I've played since my lawful good fighter/magic-user back in the days of pen&paper D&D).

Sometimes characters go down a dark path. Then, I suppose, we still have to follow them. I have to be in a certain mood to continue Olaf's story, because he is so different than me, but when that mood strikes me it is a darkly fascinating trip.

I've even started to create the germ of a story (in my mind) where Maia and Olaf are something like mirror aspects of each other and they are somehow aware of each other. Like they each exist in a parallel universe of Cyrodiil -- and in each other's minds -- but which is real and which is the dream? The nightmares Maia has (aka, the "life" of Olaf) drives her evermore towards pursuing justice, all the while she is tortured by the fear that on some level she is connected to the evil he does. And Maia's good deeds ring as reasons for remorse in the mind of Olaf.