Well actually Opal (The one who Beast Spirit Evolved into this thing) is pretty prone to severe mood swings. Whenever she, as IceGreymon or Plesiomon (her NORMAL evolution.) wins a battle, even a dishonorable one against some Rookie, she launches into a ridiculous victory dance. She's been living in the Digital World for 11 real-world years and pretty much chooses to just glow icy blue all the time, making it awkward for newcomers to talk to her. (Newcomers are normally warned about her as well.)They're often taken aback by the fact that she's always in her spirit form... AKA completely naked and glowing ice blue. (She also makes terrible ice and snow puns all the time.)

Opal lives in Freezeland, way out in the ocean, and is one of those crazies who swims through frigid waters to get around. (We here in Minnesota have this thing called the Polar Bear Plunge...)

Boy, IceGreymon is just one colorful mishmash of morbidity.