What metaphors are used in Perfume: The Story of a Murderer by Patrick Suskind?

Two themes, or motifs, develop the qualities of Grenouille that evoke admiration and
fascination. A metaphorical comparison suggests his resemblance to an insect, namely the tick, which perches alone in the tree until the appropriate moment to fall upon its victim beneath. Qualities shared by Grenouille and the tick are unobtrusiveness, persistence, toughness, and resistance. Encapsulated within himself, Grenouille, like the insect, gives nothing to the world and endures hard days awaiting a change for the better.