"It's good to be The One."

The pair smile and giggle a bit at your joke/acceptance of the offer.

As you line up your dick with the Alien's asshole, you have to ask.

"So Robin doesn't do this for you?"
"He's nice...but maybe a bit too nice. He thinks that he'll break me," Starfire explains, "No matter how strong I show myself to be, he's still afraid."
"I'm happy to fill in for him until he wises up."

You slowly enter her hole, finding it looser than you might expect.

"My race can adjust their bodies for many things. This is one of them."
"I love aliens...and Goth chicks."
"Good save," Raven says, playfully patting your arm.

Once you're sure that she's good, you fill her up and start to fuck her.
Based on her earlier wording, she wants it a bit forceful.
She's had her share of gentle.

You grab her shoulders and start to pound her.

"Yes, fuck me hard. I need it like this. Don't worship me- fuck me."

With a little bit of flexibility, Raven leans forward to kiss you while you 'violate' her friend/teammate.

One hand goes to her own pussy.
The other hand goes to Starfire's.

Starfire cums.
Raven cums.
Starfire cums again.

Unbeknownst to you, Starfire maneuvers her fingers into Raven's asshole as she has her legs hooked.

Both of them cum again.