His Personality:

Tails is a gentle-hearted, sweet-natured and loyal fox with a positive attitude.[11] While he started out as timid and quiet,[12] he has since opened up and become more outgoing over time. Tails is not one to grab the spotlight for himself and instead, is always ready and willing to help others without asking for anything in return.

Tails has a distinct love for mechanics and he finds himself most at home in his workshop working on his next creation. Despite his great skills, Tails is very humble about his abilities,[13] never giving them many thoughts, though he has yet to discover his true potential of what he can accomplish.[14] By the time of the Lost Hex incident, Tails has become more confident and outspoken about his intelligence, though he still does not openly brag. Regardless, he has been known to mock Eggman's own creations, and sometimes Eggman himself.

When young, Tails often lacked self-confidence and courage. After meeting Sonic and gaining his support, Tails gained more confidence and belief in himself. However, this status quo, created from Sonic's authority over him, initially placed a mental stranglehold on Tails that made him dependent on Sonic. As such, he often lacked initiative and confidence when alone. However, a turning point for Tails came during the Chaos incident; when Station Square was in danger of being destroyed, Tails was the only one who could stop this. With Sonic nowhere to be found, Tails realized that he could not depend on Sonic forever and had to try on his own. After saving Station Square, Tails realized he could be independent and support himself without Sonic, and all he needed was determination and faith. Since then, Tails has become more independent, self-confident, motivated and brave, rising up to be a real hero when needed.

Tails' profile, from the Xbox 360 version of Sonic Generations.

During their earlier adventures together, Tails strove to become just like Sonic by replicating the mannerisms he found admirable. In this period, Tails was content with being Sonic's sidekick as he was just happy to hang out with Sonic. As Tails grew as a person, he would still remain as close to Sonic as ever and look up to him as he has always done, but his esteem about Sonic's heroics have dwindled, as these days he cares more about inventing than Sonic's heroic deeds.

Despite his development, Tails is still a bit timid at times and can sometimes sink into self-doubt during moments of distress. He also tends to call for Sonic and rely on him in times of weakness. However, he is always willing to support his friends with a clear mind.[15] Additionally, he hopes to one day be self-sufficient and independent like Sonic to prove he can be relied upon.[14] Also, even though Tails still enjoys being Sonic's sidekick, he believes that he can do almost anything if he puts his mind to it.

Despite his intelligence and general fearlessness, Tails is afraid of lightning and can be naive and big mouthed, such as during the Project Shadow incident, when he accidentally confirmed Eggman's suspicions that the Chaos Emerald that Sonic had was a fake, thus ruining the heroes' plans. Tails also hates feeling useless or being ignored, as seen in the cases when he is talking to Sonic. He also gets very angry when someone insults or seemingly ignores his mechanical skills and takes it very personally, as seen when Wave the Swallow mocked his self-customized Blue Star; or when he became offended after Sonic decided that Eggman should shut down his Extractor even though Tails was more than capable of doing it himself.

Tails has a tendency to talk techno-babble, much to the irritation of his friends, such as when he tried to explain how an Extreme Gear worked, meaning that Tails does not always use tact in a situational matter. Nevertheless, Tails is supportive of his friends, willing to be by their side no matter how dangerous the situation might be, and will do whatever it takes to help them, even if it means sacrificing himself for them.

Ref: https://www.youtube.com/watch?v=Wqdh7z4T5vo