Best Defense is no offense
When I taught high school, I noticed that if a boy didn't know how to answer a question, he would look irritated or glum. Girls, however, would usually smile and frequently giggle. In the beginning I was irritated: there was nothing funny about my question. But I learned something that helped me understand self-preservation Sixes. When some people are afraid, they smile. When I was much younger I would walk through the park and inwardly rejoiced at how many women would smile at me. When I studied self-preservation Sixes, I learned once more that when people are afraid, sometimes they smile. The women in the park were not flirting, they were defending.
Self-preservation Sixes do this as a lifestyle. They use smiling and warmth to make friends with what they perceive as perceive as a hostile environment. Tom Condon is a movie buff and told me that Julie Roberts, a six, goes around to all the camera operators and set helpers and makes friends with them. Then she can relax and get to work.
Because they see other people as a threat to them, they make sure they do not appear to be a threat to you. They may be excessively modest and shrink from any comparisons (unless they have a strong connection to Three). If they are working for a boss, they will work hard but make sure the boss knows they don't want his job.
The belief that the world is a dangerous place shows up also in their homes. They are often homebodies, creating a sanctuary to which they flee. I know one Six who lives in a small safe rural town. He locks and deadbolts his doors. What he doesn't find incongruous is that his doors are largely glass! The locks are largely symbolic, and that is usually a tip-off that an Enneagram style is in play.
Self-preservation Sixes specialize in lurid inner scenarios, a kind of horror film they direct that always ends up with the worst that can happen as the most likely to happen.
Self-preservation Sixes combine both a strongly negative world-view with a warm and positive personality. No wonder they are perceived as contradictory.