Between her tits

Your dick slides right into the lovely crevice that exists between Starfire's gorgeous, orange tits.

"Oh...that's fun," she says, "You already had the blowjob. You want the titjob?"
"Apparently so," you say with a smile.
"Happy to let you. Fuck them."

You nod as Starfire presses her tits together around your hard cock.

You fuck her tits like it was her pussy as she smiles.

She gets pleasure from giving pleasure, which does explain why she is so open sexually.
When someone fucks her, she enjoys it and they enjoy it...which makes her enjoy it more.

She lets you use her.
You love it.

After a few minutes of this, you feel an orgasm coming.
You warn her.

She simply nods and closes her eyes.
Alright then!

You let loose, cumming all over her face, with some dripping down to the top of her tits.

"Yummy," Starfire says, recovering for her own mini-orgasm, "Are you going to clean me now?"