Alright, I'll play. Not nearly enough renegade in this thread.
Name: Carrie Shepard
Background: Colonist
Service Record: Ruthless
Class: Infiltrator
Alignment: 75% Renegade
1. Her ultimate goal is the preservation of the most lives possible. "Ruthless calculus", as Garrus calls it. This has led to numerous decisions viewed as questionable by many. Her constant focus on the bigger picture has led to the extinction of the Rachni (twice), the sacrifice of the X57 Asteroid workers to kill Balak, the sabotaging of the genophage cure. The same goes for Torfan, which she deems was an unpleasant necessity to make sure those Batarians never touched anybody again. This has also led to a major crisis of conscience by the time ME3 rolls around. She doesn't make any apologies for her choices, believing them to be right, but she hates that she's the one that is constantly forced to make them.
2. Eventually, she embraced working for Cerberus. She wasn't partial to many of their experiments, but what she saw was them getting results while the Alliance sat idly by. This led to her giving the Collector Base over to The Illusive Man. This proved to be one of the only decisions she truly regrets and continues to haunt her long into the Reaper war.
3. She couldn't see involving herself with anybody during her service, particularly not a member of her crew. If it could impair her judgement in any way, she couldn't allow it. This stance began to fall apart as the Reaper invasion grew imminent. After several weeks aboard the Alliance retro-fitted Normandy SR2, she developed fellings for Communications Specialist Samantha Traynor. Since the beginning of their relationship, Shepard has faced an internal struggle; feeling guilty for allowing herself any happiness and trying desperately to reconcile the person she is around her friends and around Traynor with the person willing to make the hard choices. Deep down, she's afraid that she's found someone she couldn't sacrifice for the mission, and she knows how hypocritical that is.
4. Kaidan had been one of Shepard's first real friends during her service, although they talked very little after the SR1's command was handed over to Shepard. This was a result of Kaidan's obvious feelings towards her, which she desperately wanted to avoid. Regardless, she was not about to sacrifice him on Virmire. They never really reconciled until after the Cerberus coup. Shepard was happy to have Kaidan back. She admired him deeply; the paragon to her renegade.
5. The frequent viewpoint that Shepard's decision to sacrifice the Council during Sovereign's attack was a political move for humanity infuriates her. It was a sacrifice she felt she was forced to make in order to ensure that the Reaper was killed. She doesn't know if they could have saved the Council and also defeated Sovereign. She tries not to entertain the hypothetical, always fearing she may have made the wrong choice.
6. Shepard saw the cost of idealism on Mindoir during the raid. It ended in countless deaths that might have been avoidable. She blamed herself for the death of her own family for many years. Although she has put the event long behind her, she'll never forget the overwhelming smell of burnt meat.
7. Though she has made countless sacrifices, she avoids them whenever possible, as her goal has always been saving the maximum amount of lives. She immediately recovered the Cerberus SR2 crew when they were abducted. Because of this policy, she inspires deep loyalty from her crew who knows that their commander would go to great lengths to save them. On the flip side, she mostly attracts those ready to die for the cause. She believes these people - those who know what they all must be willing to sacrifice - to be the best of the best.