You have a relationship with someone, anyone, and this is a regular relationship, like the one you have with the teacher of your child, or your next door neighbour, or your colleague at work.
You know this person but not very closely, and you keep a good rapport with them as there is not any problem between you and them. Until one day you say or do something unusual or oppose to something they do, ask an unwelcome question. Then you see that same calm and kind person, all of a sudden, to become a totally different being, turn into a fire-spitting dragon in front of your eyes, which surprises you immensely as it is not a behaviour that you expect from that person at all.
Because, when there is no problem between people, it is easy to go on in good terms, the question is; how they react when the unexpected happens. Do they keep their cool, do they react emotionally or rationally, do they digest the situation instead of giving an immediate reaction? Do they get mean? How their facial expressions change when they are angry? How do you act when you feel verbally attacked by someone in a way that is unfair according to you?
Next time you get angry, try to get out of your skin and look at yourself from a distance, be conscious about your reaction. Because you are only responsible of your own words and actions, and you cannot change others, but you can lead by example and if you are consistent in your consciously improved actions and words, you might start seeing a shift in others’ attitudes and feedbacks towards that direction too.
Though keep in mind; the real personality of a person comes out in times of stress, discomfort and conflict. If you don’t like what you see in such conditions, especially after giving a second chance, then stay away from them as much as you can.