Many of the methods we’ve used in the first two stages of this meditation practice can also be used in the third. You can simply call the neutral person to mind, see them in your mind’s eye, happy and smiling, and wish them well. You can use words or phrases to do this.
In your meditation you can use your imagination and share some beautiful experience with the neutral person. You can also use your imagination to visualize meeting them in real life — but this time you’re going to imagine behaving in a more friendly fashion than usual.
Isn’t it amazing! Human beings are the most complex life-forms on the planet. We have a richer and more multifaceted experience of ourselves and the world than any other creature we know of. And yet we take each other for granted so much.
Think of someone you see frequently but never think about much. This person has a rich, unknown, mysterious life. What makes them tick? What do they do after work? Do they have a family? What was the last book they read? What dreams and ambitions do they have? Do they like their work? You can simply develop a sense of wonder at all of this, using your meditation practice as an opportunity to slow down and connect.
Here’s another thing you can try: if you have managed to give rise to an emotional attitude of Metta in the first two stages, then you can simply extend this to the neutral person. It’s as if in the first two stages of the meditation practice you’ve kindled a fire, and can just invite the neutral person to come and warm themselves.