Batman: The Ultimate Evil is a novel written by Andrew Vachss and published in 1995 by the Warner Aspect imprint of Warner Books.
 Vachss was an attorney specializing in child abuse cases, as well as a crime novelist best known for his series of books featuring the character Burke, a private investigator who also takes on child abuse cases.
 A representative from DC Comics approached Vachss about the possibility of writing a novel featuring Batman.
 Viewing this as an opportunity to reach a completely different audience, Vachss agreed and wrote a draft.
 He continued with his themes concerning child sexual abuse and explored the topic of child sex tourism.
 The publisher required Vachss to follow certain rules, like making a clear distinction between fiction and reality and prohibiting the Batman character from killing, cursing, or having sex.
Andrew Henry Vachss (born October 19, 1942) is an American crime fiction author, child protection consultant, and attorney exclusively representing children and youths.
Don't!
 Buy!
 Thai!
 was a campaign initiated in the early 1990s by child welfare advocate and author Andrew Vachss to boycott goods and services produced in Thailand until its government introduced formal and practical reforms to significantly curtail the prostitution of children.
Robert Hayden (4 August 1913 – 25 February 1980) was an American poet, essayist, and educator.
 He served as Consultant in Poetry to the Library of Congress from 1976–78, a role today known as US Poet Laureate.
 He was the first African-American writer to hold the office.
Strega (Italian for "witch" or "sorceress") is a hardboiled detective novel written by American author and attorney Andrew Vachss, first published in 1987.
 The story features the pursuit and destruction by the protagonist Burke, an ex-con private investigator, of a pedophile ring involved in trading child pornography via telephone modems.
 The novel was written and published long before social concern over the use of the Internet for spreading or trading child pornography became widespread.
 It is the second novel in the Burke Series.
Burke is the protagonist of the Burke Series, a series of 18 crime novels written by Andrew Vachss.
A startup ecosystem is formed by people, startups in their various stages and various types of organizations in a location (physical or virtual), interacting as a system to create and scale new startup companies.
 These organizations can be further divided into categories such as universities, funding organizations, support organizations (like incubators, accelerators, co-working spaces etc.), research organizations, service provider organizations (like legal, financial services etc.) and large corporations.
 Different organizations typically focus on specific parts of the ecosystem function and startups at their specific development stage(s).
Veil's Visit: a Taste of Hap and Leonard is a collection of stories and excerpts by American author Joe R. Lansdale featuring his longtime protagonists Hap Collins and Leonard Pine.
 The eponymous first story was co-written by longtime Lansdale friend Andrew Vachss and ends with Lansdale "interviewing" his two heroes.
 This book was published by Subterranean Press as a limited edition hardcover and trade paperback and is long out of print.
In The Church of Jesus Christ of Latter-day Saints (LDS Church), the Priesthood Correlation Program (also called the Correlation Program or simply Correlation) started as a program to reform the instruction manuals and curriculum of the different organizations of the church.
 Its scope quickly widened and Correlation came to have large effects on almost every aspect of the church including doctrines, organizations, finances, and ordinances.
 A significant consequence was to centralize decision making power in the priesthood, particularly the Quorum of the 12 Apostles.
 More recently, the function of the correlation department has shifted to planning and approving church publications and curriculum and keeping unorthodox information, doctrines and other undesired concepts from being introduced or revived.
The "Burke" series is an 18-book fiction series written by Andrew Vachss, centered on a man named Burke and his battle against child abusers.
 The series is written from Burke's perspective in the first person.

Question: What professional function was served by both Robert Hayden and Andrew Vachss, although for different organizations?
Answer: consultant