Ollie Sparks is the little brother of Mr. Boldova, (a.k.a. Samuel Sparks). He is first mentioned by names in Midnight for Charlie Bone when Fidelio Gunn says, during the feast after the ruin game, "Last year, a boy called Ollie Sparks disappeared for 3 days." and tells a little more about what happened afterward. Earlier in the same book, however, when Emma Tolly is imprisoned by the bloors, he tries to help her escape, though after Manfred Bloor's threat of no more jam. He is next mentioned after that in Charlie Bone and the Blue Boa in a note Emma found on Mr. Boldova's desk:

My dear Samuel,

We have it on good authority that the shifter is heading your way. ... I have resigned myself to losing Ollie, although your mother still grieves. She can't stop herself from buying the jam he so loved. ... I know you feel your brother's loss as deeply as we do, but you must give up the search.

Emma later has a conversation with 'Mr. B' about the note. She tells that she thought Ollie went home, but the art teacher tells her that he was going home with a Miss Yewbeam, but went to get an orange and was never seen again. She also told him about her experience imprisoned by the Bloors.