People just can't make themselves fall asleep. In fact, the harder I "try," the more elusive sleep becomes. And I clearly recall needing a long, long time to fall asleep as a very young child. It was out of my hands.
You little guy might be a little overtired when he asks for his pacifier. That also requires more time to unwind for most little kids. It might be helpful if you were to start him toward bed a bit before that's likely to happen.
Other things that can mess with with a child's ability to sleep is emotional tension in the household (maybe only specifically about "bedtime"), television or screen time within 2 hours of bedtime (the stimulation and blue-light end of the spectrum interfere with the production of the sleep hormone melatonin in the brain), lack of enough daytime illumination, lack of exercise and active play, exposure to nervous-system irritants (in many common house-cleaning and laundry products), and exposure to certain food colors and preservatives.
But if you can eliminate all those causes, and he still takes a long time to fall asleep, then he's possibly just one of those slow sleepers. I think that includes a fairly large segment of the human population. You may need to adjust his bedtime to accommodate so that he doesn't become sleep-deprived.
Here's an extremely informative website on children and sleep: http://www.med.umich.edu/yourchild/topics/sleep.htm