As the morning rolled around, the same did Eevee in his bed, rolling around before springing from his bed and quickly checking his belly, he fondly remembers something happening at night, but he's not sure if it was just a dream or what, as his belly seemed to be at it's normal size again.
The confused little mon started trying to remember what happened, and he quickly realized when he pressed onto his stomach gently and with an embarassing sound some air flew out of him trough his tail hole. 
He remembered everything yet was confused about his feelings towards inflation, mostly everyone in the household was into it at least slightly, yet he was the only one that never tried it before until now, and he weirdly liked something about it.
Pondering alone would be no good though, and so he decided to talk about it with his best friend out of all the Eeveelutions in tge house, and that was Vaporeon.
Vaporeon was a pretty smart mon, he knew how to get what he wanted out of other mons without using any attacks or force, he was easily the hardest mon to make any deals with, and his friendship was priceless, as to how Eevee and Vaporeon became such a good friends that's a much different story i will (maybe) tell you another time.
Now, back to the present. 
After waking up and having breakfest, Eevee quickly caught up with Vaporeon on his daily walk down to the small lake near their house. At first, Eevee made it look like he just wanted to hang out, but soon decided to tell Vaporeon what he really wanted.
"Wait wait wait, you actually seriously let Umbreon inflate you? I tought you didn't wanna try the 'wicked balloony thing!'" Vaporeon giggled as they kept walking further from the house.
"W-Well yeah! What was i suposed to do! I was half asleep and he's bigger and stronger than me!" Eevee, still confused yet slightly embarassed exclaimed.
"Weeeeell, diiiiid you like it?~" Vaporeon grinned.
"Kinda, all the pressure and creaking was quite scary and uncomfortable, b-but i did enjoy seeing myself g-grow and fill up, i liked the fullness look and feeling you know?" 
"I gotchya i gotchya, hmm, well why are you telling me all of this then? Did you just need to vent about it or?" Vaporeon tilted his head.
"Well, you're my best friend here out of everyone, plus i know you are one of the mons here that fully enjoy inflation, so i wanted to ask if my feelings about it are normal?"
...Vaporeon stayed silent for a bit before bursting out laughing
"Pfft, come on silly you aren't serious right? Of course it's normal, there's no need for you to be as obsessed about it like Umbreon sometimes is, or as passionate about trying all kinds as Flareon tends to be!~" They arrive at the lake and stop, Vaporeon still talking 
"You're you, you didn't ever really wanna try inflating, and now that you happened to inflate kinda unwillingly, you at least suddenly know that you actually like something about it! For wich i am happy that my bestie now has the same interest and fun time as me!~" The Vaporeon seems to be really happy, his eyes almost shining from how excited he is.
"Hey, what do you say to me inflating you right here, right now with my water blast?~ You inflated with air but water feels different, it's a much heavier and slooshier feeling~" Vaporeon walked closer to Eevee looking him right in the eyes.
"Um, i dunno, i'm still on the edge with the idea of it and all so-" before Eevee could even continue talking, Vaporeon pulled him into a semi passionate kiss, at first it really seemed like just a really passionate kiss that Eevee quickly gave into, but as soon as he did Vaporeon took the opurtunity and started shooting water right down his throat.
At first Eevee refused to let the water down and so his cheeks puffed up with water and it started to spray out, but Vaporeon quickly took a hold of him and deepend the kiss, the water shooting straight into the small Eevee's body.
At first, just audible gulping could be heard coming from the Eevee but soon small quiet muffled moans started escaping him too.
Eevee put his paws on his now slightly bulging out belly, feeling his regular capacity already being full. He just sat there, enjoying gulping down every last drop of water his best friend was shooting inside of him and getting bigger.
As his belly grew bigger, their kiss grew ever so more passionate the longer they held it, for a small while Eevee even forgot about the inflation, but quickly snapped out of it as his belly was now touching the ground, the football belly tightening up and getting firmer, it was squishy and soft on touch, yet felt really tight and heavy to Eevee. The Vaporeon had no intension in stopping just yet, he continued shooting water down his best friend and now hugged Eevees belly to feel it. 
Eevee was getting just around the yoga ball mark and now whimpering, the tightness getting obvious as gentle creaks resonated from his belly, Eevee was squinting his eyes now but still gulping away gladly, growing bigger and bigger, the creaking getting more audible. Eevee was so tight and big, it was only a matter of minutes before his body wouldn't handle the pressure anymore, but Vaporeon stopped, with a satisfied and slightly lustfull smirk on his face he pulled apart from the kiss and rubbed Eevee's belly, Eevee was now Vaporeons huge waterballoon, filled to the brim, tight and heavy yet soft.
Vaporeon looked at Eevee and gave him another kiss, this time just a kiss, no water, just a regular passionate kiss.
He let it going for a while before pulling apart quickly gasping for air, a string of saliva between them.
Eevee, surprised by the sudden kiss, blushed, but Vaporeon didn't break a sweat and pretended like nothing happened, hugging his huge waterballoon of a friend, rubbing him, even deciding to lay on him, it was quite comfortable. 
The day just started, yet to them it felt like the whole day already passed and so they spent their whole morning just laying there by the lake and relaxing, talking, and laughing.