Stiyl's surname Magnus is "great" in Latin and has been used many times throughout the antiquity. An example is Albertus Magnus, a famous 13th Centyry theologian who called for peaceful coexistance between Science and Religion and was thought to be a magician and an alchemist.
Stiyl's hair is actually blond but he has dyed it red and goes down to his shoulders. He is a very tall man 6'7 ft high despite being 14 years old. He wears a large black priest robe with silver rings on all ten of his fingers. He's covered in jewlery on his ears and has a barcode tattoo underneath his right eye. Stiyl is always seen with a cigarette in his mouth and is a heavy smoker in general. He appests to be physically weak as seen when Touma first beats him in a single punch as compared to most other of Touma's opponents later on. His weakness is explained in his use of Innocentius which uses large quantities of energy and it renders his body weaker than others because of it.
Stiyl has a rather short temper and is very easy to tick off but he still cares for people like Index and wants to protect her from harm and has even hinted affections for her in the past. His greatest regret is being unable to save Index without her loosing her memories and even allows Index to live her life despite disobeying the orders of the church but is still loyal to it and currently remains a member. Stiyl appears to dislike Touma and loves to cause him trouble and discomfort whenever he's around him but he respects Touma because of his abilities and because of how Index is happy whenever she's with him and wants her to be happy. Stiyl is also a heavy smoker and he's always seen with a cigarette in his mouth. He hates Academy City because of how it's extremely difficult to find a cigarette being a minor and believes that a world without nicotine would be hell for him due to his addiction.