All of us take an interest, to a greater or lesser extent, in what people around us look like, what they are doing, and why they are doing it.
Sometimes, in a portrait, I go straight in with paint onto canvas... Other than riding my bike up and down the hills around here, it is the most dangerous thing I do... like tightrope-walking without a safety net!
As a boy, I used to look at reproductions of Rembrandt's portraits... the people in his paintings were so real I felt I knew them... It is his empathy for the sitter, combined with his enjoyment and dexerity in handling paint that captured my imagination then, and is what I am striving for still.
People fascinate me. Consciously or unconsciously, I have been studying their behavior all my life.
Painting someone's portrait is, of course, an impossible task. What an absurd idea to try and distil a human being, the most complex organism on the planet, into flicks, washes, and blobs of paint on a two-dimensional surface.