Very kind.
Tails is portrayed as a very kind, sweet-natured and loyal young fox with a positive attitude and always willing to help out whenever he can. He was very shy when he first met Sonic the Hedgehog, but gradually opened up and became Sonic's best friend.
Initially timid when he had first met Sonic, Tails has slowly opened up and become more outgoing over the years, though he still remains reasonably shy from time to time. This trait may be due to the fact that he was a victim of bullying or teasing because of his two special tails before he started hanging out with Sonic. Tails is not one to grab the spotlight for himself, nor does he seek it. Instead, he is always ready to help others when the time is needed.