Kovu is a 16-year-old that works for both Herbert and EPF, but the EPF agents, except Rookie, don't know that. He tried to make Rookie forget but he said he would keep the secret if he stay away from SnowDropp. Kovu accepted that because he didn't want to lost his job, even if SnowDropp got suspicious.
Kovu lived with his family until they ended up caugh by Herbert, who saw his abilities and decided to keep him. He promised that he would spare his family if he works for him. After he knew his family was dead, he left Herbert to join the EPF again.
SnowDropp is the only relative alive of him, so he is very protective of her. She usually don't care too much about him or his skills, but she sure care about him, and she likes to stay with him. When she recognized Kovu she rushed to hug him.
Does he have any power?
No, unlike SnowDropp, he is a common penguin.
When he discovered his family was dead?
When SnowDropp went to spy Herbert and heard him say something.
Who's his best friend?
Dot, he also have a crush on her.
His special ability?
He's good at math, disguises and mimic voices, specially snowdropp's.
If Snowdropp is his only relative alive, what about her parents?
Well, Kovu was adopted, so they aren't his uncles, in reality. And as SnowDropp is also adopted, they have a connection.
Does he have any puffle?
Yes, he lives now with SnowDropp, and both have puffles. Snowdropp have one called Kouichi and Kovu have one caled Lavah.