Best of Both

Flash Sentry didn't understand why his girlfriend was being so cryptic, but he trusted her and just listened to what she said as she explained what exactly she was planning "OK Flash, I know we haven't exactly been intimate yet but I think it's about time we did something. Now I know what you're thinking and you're right, there isn't really a secluded place for us to have sex, however only a couple of people know where the portal actually is, so I figure I could at least give you a cheeky blowjob there after everybody leaves school by just having my legs back in Equestria and keeping my torso back here. That way people will just think you're admiring the statue rather than getting sucked off" Twilight gave him a mischievous smile. Flash Sentry was surprised at this suggestion, yet immensely more aroused, he chuckled at Twilight's idea and agreed wholeheartedly, he loved how kinky his girlfriend was.

When school was over and all of the students and teachers had left, they both went to where the portal was located "Now..." said Twilight "You just wait here while I pop back to Equestria to freshen up m'kay?" Flash Sentry just nodded as his girlfriend vanished through the portal back to Equestria.

Flash Sentry didn't understand why the princess was being so cryptic, but he trusted her and just listened to what she said as she explained what exactly she was planning "OK Flash, I know we are not exactly well acquainted, what with me being princess and you being one of many guards, but that is about to change. Now I know what you're thinking and you're right, there are many many guards I am not acquainted with, however I do have somewhat of a soft spot for you I must admit. Which is why I've selected you to help me relieve some stress if you catch my meaning, I understand you may feel trepidatious about sexually pleasing a monarch, which is why I'm going to use the portal to hide my torso from your vision so that you'll only see my legs, that way you can pretend you're just fucking some random pegasus in the ass rather than the ruler of the country" Twilight gave him a mischievous smile. Flash Sentry was surprised at this suggestion, yet immensely more aroused, he chuckled at the princesses idea and agreed wholeheartedly, he loved how kinky the princess was.

When all of the guards had been ordered to leave Twilight alone with Flash Sentry, they both went to where the portal was located "Now..." said Twilight "Once you can only see the back half of my body, you feel free to just get started and have fun with my rear, m'kay?" Flash Sentry just nodded as the front half of the princess of Equestria vanished through the portal back to the human world.

Flash Sentry waited patiently for his girlfriend to return and though he was expecting, was a bit shocked to just see Twilight's top half of her body poking out from the portal. Twilight smirked and said "You ready?"

Flash Sentry nodded and said "Yeah, I've already called my parents to tell them I'll be late home, I said I was staying behind to study for math class"

Twilight giggled and said "Maybe you should have said you needed to study for sex ed huh? Now come on and get your dick out already, I'm hungry and need something in my mouth". Ever the gentleman, Flash unzipped his jeans and pulled them halfway down his thigh, Twilight bit her lip as she saw the big bulge in the front of his underwear and practically gasped when he pulled them down to the same place his jeans were, allowing his cock to spring out of its cloth prison and very nearly smack Twilight in the face. It was bigger than she expected it to be. Twilight just licked her lips as she wrapped both of her hands around his cock and started pumping them back and forth, he was so hard that Twilight wasn't even sure he needed to extra encouragement.

Meanwhile on the other side of the portal, Flash was just staring at the big bouncy princess ass in front of him, he was still extremely nervous, that is until he saw it start waving from side to side almost as if inviting... no, almost as if begging Flash to approach and do whatever he wanted so long as it didn't involve any pussy action. Flash steeled his determination and approached before unceremoniously shoving his muzzle in between this massive fat cheeks and started licking and sucking the tight pucker of her ass hole, he knew that he would be getting the opportunity to mount this bitch and stick his cock in her booty, so he wanted to make sure that her back entrance was as slicked up with his saliva as possible. It also didn't hurt that he was a stallion with a penchant for a nice bit of willing mare ass and wanted to indulge in just a little bit of worship first.