She kinda acts more maturely. She's fond of gambling and quite good at it (afterall, Monaco is a gambling center.). And she also doesn't mind if some random guy (pertaining to Seborga) would come flirting on her.
That's Monaco. She's a bit uptight and act very mature eventhough she sees herself as France's little sister. She's an excellent gambler and If you go against her you will lose because she almost always wins.