Then why did Tessa's house always seem to be the real thing, and ours its unimaginative ugly sister?

In Cinderella, the ugly sisters are the main character's stepsisters.

The two ugly sisters of recession, nationalism and protectionism, are abroad.

The ugly sisters were effective, if no more.

You want me to find a husband for your ugliest sister?

Cinderella and her ugly sisters get an invite to the Prince's ball.

Analysts and investors generally agreed that the company was looking less like the semiconductor industry's ugly sister.

Wasn't it traditional to make approaches to the ugly sisters first?

"It always seemed that Six was the ugly sister under Don's umbrella."

"You went to visit that ugly sister of yours, didn't you?"