NE dominant types (ENTP/ENFP) are often considered the most "introverted of all the extroverts." I believe it is our Ne (Extroverted Intuition) that allows us to go off into our own heads for long stretches of time, and then we pop up and look for others to try out what we've come up with. We are able to get lost in our own heads and not notice where our energy is coming from, but sooner or later, we get an "itch" to be around the energy of others. Some people even bring up the word: "ambivert" when speaking of us.
I do not always feel the need to speak up and be the center of attention. I pick and choose my words very carefully. I like to observe others before I join in, yet, I do enjoy being in a group of people (usually 25 or less). I like being able to choose my interaction level depending on my mood at the moment. I generally like bouncing my ideas off others and seeing which ones stick, which ones don't, and how the interaction provides me the opportunity for me to improve upon them. I want to hear other perspectives precisely because they are different from my own.
What cannot be faked about either ENFP or ENTP is they do tend to have a lot of enthusiasm when they are really into what it is they are doing, and their enthusiasm tends to be infectious. There's a certain amount of charm about us that is undeniable. When we really turn it on, people tend to notice.