Lesath Lestrange is a 5th year Slytherin student during Harry's first year. He is the son of notorious Death Eaters Bellatrix Black and Rabastan Lestrange, who in particular tortured Alice and Frank Longbottom (Neville Longbottom's parents) into insanity and are both serving a life sentence in Azkaban. Lesath is often bullied for this.
In October, Harry and Neville help Lesath against bullies. Lesath then believes Harry "can do anything" and begs him to get his parents out of Azkaban.
When Bellatrix Black escapes from Azkaban, Lesath believes that Harry did it and pledges allegiance to him in spite of Harry's protests.