William is a young grey mouse who is the best and closest friend of Angelina and Alice in the first series of the show and the books. Other times when he's not hanging out with Angelina or Alice, he's sometimes seen with Henry, and he acts a little bit like an older brother figure or family member to Henry. In most episodes, when William is around or talking about Angelina, it is shown that William has a crush on her but she is still in love with Marco it's unknown if she returns the feelings he has for her.