So, a possessive noun is usually used to indicate who or what has something, like "The Dogs' ball."
To change this form of children,plural, to a possessive noun, you will want to add an apostrophe, and then an s. It changes to this:
Children's
Parallelism, if you mean the way he spoke. which is mostly meaning heavy adjectives.
Explanation:
Renfield's face is bashed and bleeding and his back is broken.