One example is that everybody needs food, water, clothes and shelter to survive so those are just the basics
another ex is that everybody needs a friend or friends in life to help them go through things, physically, emotionally and through the good and bad, and you need friends to talk to as well like sharing common interests.
Mercutio Is a mischievous man so is Romeo and it was their idea to read the ball where Juliet was so Mercutio does shape Romeo’s character in that they want some thing both of them.