In a manga I'm writing, about people at college having magical superpowers,(better than it sounds), there is a team of three kids from a rival college that show up for the Tournament Arc. They all have blue hair, go by the collective nickname "Sea Siblings", but I'm trying to make each one of them a seperate character in their own right, even though they were introduced together. There's a huge angry jerk jock on the american-football team, a hot-but-really-mean on the Ping-Pong team, and a creepy short kid who's hair always covers her eyes, and never speaks, but occasionally does "Crazy Evil Little Girl Giggling" when fighting. I've already decided that she'll have water/ice powers, but what about the other two? I'd like them to be somewhat cold/water/ice-themed, since they are from a fictional country based on the north pole+russia+canada, but it isn't really an issue.
My manga is slightly cynical and dark, and the main characters are a tall, sarcastic Bishonen with lightning powers, and a maybe-evil butcher with control over the dead, and blood. The morality is usually weird, two shades of grey fighting instead of black vs white. Also, most of the characters in the manga are very powerful. The age rating for the show is PG-13, and the Necromancer's blood isn't his own, it comes out of a portal at high speed, like an evil blood-related version of water powers. The blood isn't even human blood, it's goat blood. Somehow, everyone notices that.
In the story arc they are introduced in, in the middle of their respective matches, they start attacking the other students. It then turns out to have all been a set-up, and the two colleges go to war, with huge fight sequences and awesome moments every few pages.
So, can somebody help me with characterisation for the three Sea Siblings?