Mercedes faces trial on two counts of perverting the course of justice this week following her twisted plot to frame love rival Mitzeee Minniver for attempted murder and child kidnap.
Although Mercedes has hit rock bottom since being caught out a few weeks ago, Metcalfe told E4.com that she doesn't deserve any sympathy.
The actress explained: "I think my character's never had a happy ending because she can't. I don't think with Mercedes there ever is a happy ending. Just when something might go her way or something's going to go right for her, she destroys it - and I wouldn't have it any other way. It makes great drama.
"I don't think Mercedes will ever change, and I don't think I really want her to. I love playing her the way she is - fun, feisty, depressed, up, down, left, right! You don't know where she's going to go next, and I love her that way."
She continued: "I have no sympathy whatsoever for my character Mercedes. When people [said] on Twitter, 'Oh poor Mercedes, Riley should get back with her', [I thought], 'No, she's horrible'.
"I love her that way and again I wouldn't change her for the world, but I have no sympathy for that girl whatsoever. She gets everything that's coming to her."
Metcalfe also confessed that Mercedes doesn't regret her vicious attempts to blacken Mitzeee's name.
She said: "I don't think Mercedes has any regrets whatsoever. I think she does what she does at the time for a reason, and she'll deal with the consequences later, whatever they may be!"
Hollyoaks airs Mercedes's trial all this week at 6.30pm on Channel 4.
Watch Jennifer's full interview in the video below: