Redheaded Stepchild 

Treated with dislike, distaste, much the same as a "second class citizen." Less important. Ostracized, at times.
(If the stepchild had red hair, and the parent didn't, people would assume that the parent was the step-parent. This is obviously an ignorant assumption, since the gene for red hair is not a "dominate" gene, but a "recessive" gene -- it would skip generations before showing up again.)

In the state of Alabama, it is well known that Auburn University will always be the Redheaded Stepchild to the University of Alabama, when pertaining to football and all other things athletic - and chess. RTR!

Redheaded Stepchild by EvilRedHet September 29, 2010

a red headed stepchild's rental mule 

Something or someone needing or getting a very severe beating.

The next time l catch you punks hanging around my girls, l will beat you like a red headed stepchild's rental mule!!!

a red headed stepchild's rental mule by I, Wreckerrr October 10, 2016

red headed stepchild 

A child who is obviously not your own, a child who is treated worse than other children in the family

I beat him like a red headed stepchild.

red headed stepchild by Vindriss December 28, 2005

red headed stepchild 

With red hair being rare, a child born to non red headed parents was often assumed to be the child of an affair. Thus was treated badly, usually in the form of beatings.

I'll beat you like a red headed stepchild.

red headed stepchild by Little Red Knitter January 28, 2009

red headed stepchild 

A person or group treated without the favor of birthright.

The boss treats this department like his red headed stepchildren.

red headed stepchild by Tim September 13, 2004

red-headed stepchild 

Applied to one who does not fit in and is shunned for the differences and/or is bullied at a high degree

By marrying his daughter, Woody Allen was considered to be the red-headed stepchild of Hollywood.

red-headed stepchild by Big Mike October 31, 2004

Red-headed stepchild 

In business, this is a product, remote office, employee, etc., who doesn't get respect. The moniker stems from the popular slang phrase "beat you like a red-headed stepchild." Often times, the disrespect is undeserved.

If a product is an embarrassment to a company, it is the company's red-headed stepchild.

The satellite office was outperforming the head office statistically, but because it created work for people in the head office, it was treated like a red-headed stepchild.

Because the Edsel didn't sell well, it became Ford's red-headed stepchild.

Red-headed stepchild by Glenwood October 1, 2006