OP image: 
https://s1.desu-usergeneratedcontent.xyz/mlp/image/1557/20/1557203315933.png
https://derpibooru.org/images/666523

>Celestia wants Anon
>No, she really wants Anon
>Her heat finally caught up to her after forgetting to reapply the numbing spell
>And now, after eons of suppression, it came with a vengeance
>She knows none of her ponies would survive her cycle
>Being crushed under her gigantic flanks before she even began
>Or if she got an earth pony to survive that, it surely wouldnt be able to tend to her fire before passing away from exhaustion
>So the only one that could possibly aid her is this creature
>Taller than her ponies, but still small enough for her to marehandle
>He is even lighten than expected, about a tenth of her weight too!
>But she cant just attack him openly in the day as he goes around in her castle
>Seeing her sister frustrations, Luna comes with an infallible plan
>Having deep knowledge in the art of horse medicine, Anon quickly rose to the rank of castle doctor
>So if she were to get a fever, no doubt he d visit on her own chambers
>No eyes to see, no witness behind
>Just her and Anon, alone...
>The thought alone is enough to make her squirt
>In middle of the day court
>'Just one more and you re free, hold it together mare' she thought
>Cause today is the day the sun is getting its worthy praise

>The day ended without many news
>Besides with the sun princess looking like a tomato from holding back
>This will be great to sell the history
>Some even asked if she was fine
>But besides a little dreamy and wet as a dam, there wasnt anything to worry
>Passing by Luna, the swing in her steps told all her sister needed to know
>That and the massive swing from her fat flanks almost hitting the blue mare in the face
>It was time to put the plan in action
>Didnt take long for Anon to get to Celestia chambers, she barely had time to remove her attire
>But the sun princess getting sick was a national worry
>Not like she ever got sick on her life, but Anon didnt knew
>Clueless, he laid down his doctor bag by the bed and patted her in the neck
>Celestia moaned loudly from the touch, as Anon thought she had some cramps from working while sick
>Massaging her neck, Celestia shivered from the ministrations
>Knowing the danger of working on a horse so big, he slowly moved to her side, caressing her back and directing her towards the bed to lay her down
>Two could play that game, as Celestia wordlessly directed him to be by her side while she brought both of them to bed
>All the while getting a back massage
>Before she laid down, anon gently grabbed her chin to see how red she was
>Her deep breathing told him all he needed to know
>She didnt had any fever from what he felt
>SHE WAS HAVING TROUBLE BREATHING
>Surely all those years must have caught on to her tired lungs
>Celestia on her part couldnt help but let her tongue lull out of her mouth as he let go to push his bag to the ground
>Gently settling her down, he asked for her to lay on her sides, which the mare obliged
>He hadnt worked with such a big horse on Equestria, but he hasnt gotten the nickname Dr. Horse for nothing
>Putting one hand on her shoulder blades and another on her flanks, he leaned in on her sides, eyes closed while trying to hear something
>The hand on her flanks was right in the middle of her sun, grabbing only the middle orb with how big her flank was to him
>Feeling this she couldnt hold it anymore and began to rise
>Anon tried to hold her down but she was too strong for him
>And merely extending her wing was enough to make him lose his balance and fall back on the bed
>With a quick burst of magic, a click came from the door
>Now the fun could begin
>Turning around, she sat besides the confused human, sizing him down
>Slightly lighter than her ponies, but a straight frame long enough for both of them
>Shame for no muzzle and the tiny mouth, but this would have to do
>Anon was already struggling to get free, but a single hoof of hers held him in place
>She just wished his head wouldnt crack, as she lifted herself and moved her flanks to be above his face
>Seeing that, Anon hands shot upwards to the side of her flanks, trying to divert it somewhere else
>But was not to be, as the tons of plot fell on his face
>Many ponies would be jealous, not caring about giving their lives for such a purpose
>But Anon was no pony, and kept trying to resist the inhumane weight atop his head
>That only enticed the princess more, making her grind herself along with his movements
>Wasnt long before her first release came, drenching him in her juices and making her lose support of her rear legs
>Without the support, her twin suns fell down with all their mighty and an audible pomf, Anon surviving only thanks to the mattress
>But Celestia was far from done, she needed more
>Seeing how he was still alive after being almost half buried under her flanks, she called upon her magic to claim her prize
>Anon clothing was gone in a flash, and in front of her was something that could not lie
>For all his struggles and wishes to be free, he was hard
>That invigorated her once more, grinding on his face slowly as she brought the tip of his alien member upon her mouth
>The salty taste was a nice bonus, weird, but not too bad
>It was then that something small and wet made its way inside her cavern
>She had licked it once, but apparently Anon had just licked her back...and he wasnt stopping
>Shivering with pleasure, she was set to not be beaten, and she engulfed his whole member at once
>It didnt matter if he was big or small for his race, her big muzzle did short work of it without even needing to deep throat
>Her reward came as soon as she sucked it, with big and powerful lungs like her, Anon couldnt ask for anything stronger
>And his moans shook her from her insides, giving her all the more pleasure
>Bobbing her head up and down was rewarded with more frantic licking on her love tunnel
>And soon enough, she lost the match of who would resist for longer, cumming once more while just having a small taste of what was to come from the human
>Concern actually creeped in, having gone so long without anything coming out from him
>Any stallion would have given her his seed as soon she gave her patented princess succ
>Lifting herself up she looked down to the creature laying down below her
>The mattress had conformed to her size, leaving two craters besides his head
>But after all that, he was breathing
>Perhaps it was time to get to the main spectacle
>Licking her lips, she turned around, aiming her huge assets with his little pole
>"Celestia-" - he tried to say, before she leaned down and kissed him
"Just enjoy it, my little human"
>And with that, the two suns dropped at once, not giving him any time to prepare for the impact
>Said impact was so great, so full of need, that if lifted Anon up as she rose again
>Before coming down with the same force, not leaving any time to relax or take a break
>Anon moved his hands towards her flanks, trying to not get crushed under the sun and to try to slow down on her enthusiasm
>Soon enough she found a good rhythm, not going so strongly but also not too soft as Anon hands firmly pressed against her fat buttocks
>While she never expected any stallion in Equestria to be big enough to fill her, Anon never ending hardness made up for it
>Not once had he shot his seed inside and she had came twice more
>Thrice
>She started slowing down, five orgasms and a sixth at the door tiring her enough
>Anon tried to pick up her speed, but couldnt move much with her weight over him
>So, with him still inside, she turned over hoping he d pick up the pace
>And pick up his pace he did, grabbing her chest fluff with one hand and a back hoof with another
>She lost count by the 8th orgasm and he still didnt stop
>As she looked down their eyes met, and he moved his hand form her chest fluff to grab her head
>It was too far for him to reach, and he was slowing down, so she lowered it herself to see what he wanted
>Swiftly, he grabbed her muzzle and kissed her
>With another thrust, he let his seed finally flow inside of her, sucessufully clenching her fire for the day
>Once done, Celestia pulled her head away and let it fall back on her pillows
>The human also laid down, but on top of her with his head on Celestia's chest fluff, soaking it with her own juices from before
>But she also got to feel his member shrink while inside of her, as he didnt take it out
>Warping her hooves around him, she wondered what she could try with him on the following day
>Now that she had claimed him, there was no need for trickery
>And adding her vast knowledge of magic to this sure sounded like it could be fun~