First Line Challenge: To save his own life, he would have to kill. (Somewhat altered, as you will see.)
Author's Note: When reading this prompt, I automatically thought of Voyage of Temptation. Specifically, the scene where Tal Merrick is taunting them with the fact that Satine is a pacifist and Obi-Wan risks losing her affection by going into action. Just something about the look on Obi-Wan's face sparked this small bit of internal dialogue.
To save her life - not to mention his own and the countless others aboard the Coronet - he would have to kill. The irony was not lost on Obi-Wan. Merrick was right. He was no stranger to violence. And, though he loathed taking a sentient life, Obi-Wan was far more prepared to do so than Satine. Even now her hands shook as she held the blaster, the knowledge that pulling the trigger would not only be the death of Tal Merrick but it would also sacrifice the peaceable tenants she held so dear. He could not let her face such a choice. He would do what needed to be done, even if she despised his actions. At least she would live to be further disappointed by his choices. Obi-Wan could live with her anger. After all, the Jedi Order had taught him well. Internalizing regret, concealing pain, and doing what must be done was his specialty. Yes, to save her life, he could do it - become the thing she hated most, a murderer.
In the end, he was saved from doing so by his former Padawan. He reproved his young friend with a resigned, "Anakin!" Yet, Obi-Wan could not help but be grateful. Skywalker had saved him not only from losing a part of his soul in killing Merrick; his friend had kept him from losing something far more precious. Anakin had saved Obi-Wan from losing Satine.
Endnote: I know this was terribly short, but the following prompts will be longer.