You have to.

You look at the horsecocks. The centaurs are already lining up behind Calyra, who is by now desperately squirming. This unfortunately only means that her ass is wiggling and her breasts are jiggling, making for an even more enticing sight.

You have talked about boys with your friends and once touched your ex-boyfriend down there. From your limited experience, human penises vary in size, and so do the centaurs-cocks. But even the smallest is longer than your forearm, and you will have to use both hands to grip around them. There’s no way they can fit inside Calyra.

“I’ll do it”, you say, as you step towards the tightly bound Slytherin girl. The centaurs wait as you get into position.

The situation is extremely awkward. You sit on the ground, between Calyras tied legs. Your face is right next to her fully displayed pussy. It doesn’t smell much. Her natural musky odour is mixed with a slight rotten tone, most likely the goblin seed. This close, you can see some red marks from the ordeal she endured earlier. And then your observations are cut short by a cock!

It looks remarkably similar to your ex-boyfriends. However, it’s just so much larger. The shaft is longer than your forearm, and the glans is larger than your closed fist. The outer end of it is reddish, almost like a humans. About halfway there is a bulge, and the part nearest the body has the same colour as the centaur, in this case brown. Above all, it is very clearly a cock, just so much larger.

You put your hands around it. If cupped, you can reach around it. Even if you put them next to each other, you still have no chance to cover it all. Then you start moving. First a few gentle tugs up and down, as you try to find a rhythm that will please this beast. There is no reaction. No sudden jerks of the penis. No changes in breathing.

You remember the elder. Perhaps this is the first this centaur has ever been jerked of, since they are unable to do it themselves?

Since nothing is happening, you put your mouth to it. You start licking the shaft, then running your tongue along it. There is a strong taste of sweat. Do centaurs wash?

You focus your effort on the head. From underneath it, you are only able to reach the parts closest to you. But you run your tongue up and down the glans, occasionally stopping to plant light kisses directly on it. Finally, he starts to react. “That’s good. Move your hands as well.”

You do as you’re told. You move alongside it for easier access. Then you start jerking it, while still planting kiss and licking the glans. It’s almost like you’re playing an obscene transverse flute.

”I’m ready,” the centaur grunts, and you remember the purpose of this strange exercise. You line up the penis with Calyras ravaged slit, and watch in fascination as the centaur cum. And cum. And cum. There’s so much cum pumping into Calyra, much more than any human could produce. Predictably, it start dripping out of her.

“Quickly. Taste it.” You look up at the centaur-elder. You start to question why, but you’re cut short. “Trust me, just a quick lick. What does it taste like?”

The situation is bizarre. Your friend is tied to an improvised pillory, ass in the air. You have just jerked off the second cock of your life, and this time it was a centaur. And now you are being asked to lick semen from Calyras cunt.

You won’t do it! But you still obey the strange eagerness of the centaur, so you reach out and swipe some with your finger. It doesn’t smell of anything, so you give it a very delicate lick.

“It’s salty,” you report.

You can’t really tell if the centaur is disappointed. “Then it’s not goblin sperm. We’ll have to try again.”

The centaur you just jerked steps away, not even thanking you, and is replaced by a new, fully erect, horsepenis. Oh well, here you go again.