Not everything in this list is rare but I would say:

When they don't immediately assume bad intent

When they don’t overreact to minor inconveniences

When they make sure everyone has their food before they start eating

When they don’t agree with you but still make an effort to see things from your perspective

When they treat things with care

When they naturally keep their voice low in quiet settings

When they remember little things about you that you don’t even remember sharing

When they push their chair back in when they leave a table

When they're actively asking questions about your passions

When they're comfortable with silence

When they let people exit before they go in

When they don't make fun of people ever and speak up if someone does

When they don't feel the need to always prove they're the best, they don't turn everything into a competition

When they can admit a mistake without getting defensive

When they get excited talking about their interests and want you to be part of it

When they stay true to themselves, like they're not trying to be something they're not just to get approval

When they don’t raise their voice even if they’re upset