Maturity (not to be mistaken for cynicism, defeatism, or plain boringness), among much else, has a certain appeal to many - but especially to those who are themselves mature or striving for maturity. Speaking mainly of character, which encompasses the mental, emotional, and spiritual realms, here's a quick list of a few (in no particular order) of the traits that make it so:
1. Once a level of trust has been built, communication is open and clear.
2. After many lived experiences, many observations have been made and lessons have been learned.
3. Less likely to be impressed by trivial and vapid things.
4. Heightened ability to look past illusions.
5. Able to form their own opinions, revise their beliefs, and consider views and gathered input.
6. Have proved themselves to themselves, not as interested in proving themselves to others.
7. Can laugh at the absurdity that is taken too seriously.
8. Has seen enough to not miss the forest for the trees.
9. Smoothly handles what could have others stressed or even panicking.
10. Takes failure and rejection with relative ease.
11. Ambitions and aspirations go beyond worldly rewards.
12. Appreciates the simple and small - yet meaningful - things once taken for granted.
13. Solves issues and/or gets along with family and friends they may have had minor differences with.
14. Realizes we're in a game and that the rules are questionable.
15. Possesses an immense and intricate universe within.
16. A grasp on their likes and dislikes, until/unless they shift again.
17. The wittiness and cleverness that comes with wisdom and not just intelligence.
18. A long history of chances they've taken, where they led, and how they turned out.
19. Values and forges deep connections and lasting relationships.
20. Commitment, at least to what's right for them and after careful evaluation, is not taken as a suffocating cage to desperately escape from and it is instead stabilizing.
These are some of the ones that stand out for me the most. But you can surely think of more!