In spite of herself, she chooses to stay.

'What am I going to do,' Batgirl thinks, 'It is try to run back home naked or call Batman. Either way, it will be embarrassing!

If I do what she wants, maybe she will just give me my clothes back. Maybe.'

Deep down, Batgirl/Barbara has some submissive tendencies.
She's strong, brave and tough...but letting go once in a while sounded appealing.
Deep in the recesses of her brain, she's had fantasies about being dominated in a controlled manner.

For instance, maybe she's caught by Harley- like nearly happened- and not the Joker too, so the former decides to play with her instead of turning her over to the latter.

Things would keep going.
Taboos would be broken.
She'd take in new experiences with Harley...

"I'll...stay, if you promise to let me get my uniform back when we're done."
"Very well."

Ivy starts to strip out of her tight outfit, revealing her body to Batgirl for the first time.
The redhead can't help but stare.
Ivy's smile pull her out of her trance.

"So what do you want me to do," Batgirl says, hoping it is something better than she expected.
"Figure it out."

Ivy leans down on the floor with her legs spread.
It is obvious what she wants.

With a gulp, Batgirl moves into position and starts to do what Ivy wants...

It is going to be a long night.