Tails has been the easiest to fine; but he also went through several changes when I was in the process of trying to figure out what style to go with; and how to integrate the style in the other characters. As with almost any revamp I've done I wanted to draw inspiration from various sects of the official media to show my appreciation for each creator's take on Tails through his 20 year existence. :)
Compared to all the other males Tails lacks certain general masculine phenotypes: lack of thicker black or brown lips, thick brows, thinner lashes, and thinner brow ridge. He's more feminine in his look and it shows almost through his entire age up until he's an old fart.