Well a Robin is a type of bird and Robin likes adventure and likes to travel so that's a thing, as for his appearance, well the robe and blades (not going to get into too much detail about because back story) were all made by him, the robe creates an air of mystery which matches the fact that his personality and the air that he gives off, his motives, those things about him are impossible to read and pin down. As for the rest of his appearance..well the gloves and jeans are tied to a part of his past, and the shirt is a skin tight black silk shirt which allows him more flexibility in his motion matching his flexibility in planning and strategy as well as how closed off he is when it comes to letting others see the truest part of him...and..well..ya know, silk, it's like super comfortable and like the best material ever for clothes.