3rd person pov
. . . . Things started getting heated as the two monsters made out. Sans started to unbutton the flame elementals shirt, and grillby was working off the skeletal beings jacket and sweater. Grillby liked sans' cheekbone, down to his ribs. "A-ah~!" Sans let out a string of moans as each of his ribs were nipped and licked. Sans yelped as grillby grabbed the base of his spine and stroked up, and down. "G-grillby~!" Sans' voice rose in pitch. Grillby looked down at a faint glow that he knew wasn't his own and saw glowing in sans' pants in the middle of his pelvic area. Sans saw where the flame monster was staring and said "p-please, grillby please" as he bucked his hips upward towards his partner and soon to be soulmate. The larger monster proceeded to hook his finger into the hem sans' pants and boxers and yank them down in one swift move. Sans yelled out in surprise at his actions "a-ahh!". Grillby trailed his fingertips up sans' lower lips, towards his clit, making sans shudder with need. "Oh~ s-stars~" sans stuttered out with a moan. "Sans" grillby said, making sans look him in the eyes(?). "Tell me. Tell me what you need" grillby stated with a thick, breathy voice. Sans trembled as he spoke. "Oh stars, g-grillby. You, I-I need you!" Grillby smirked. He slowly unzipped his pants whilst sans watched eagerly. When he was finally fully undressed, his flaming orange cock sprung up and bobbed as sans was tempted to just ram himself down onto it. After grillby prepped sans' vaginal hole, he slowly inserted the tip of his erection into sans. Making him flinch. "Shhh~" grillby hushed sans while wiping his tears away. Grillby steadily pushed in until he had hilted inside of sans, whispering sweet nothings into his non-existent ear. After 2-3 minutes, sans shifted his hips to see if he was ready. When sans let out a moan at the action, grillby pulled out and then rammed back in causing sans to scream out his name in pleasure. "Hahh!~" grillby let out a crackling chuckle as sans suddenly yelped his name, "g-grillby~ hah, ah! t-there!". As time went on grillby started getting rougher and more desperate for release. He rutted against sans so hard that sans was seeing stars and drooling as he screamed in pure pleasure. (A/N I guess you could say grillby's a wild fire XD). As they neared the end of their coupling, grillby's flame started to grow. "S-shit.. Hah, sans! I- cumming!" As grillby came inside of sans, his flame suddenly burst and hit the roof then came back down just as quickly. Sans came at the same time calling out grillby's name. Sans moaned as the warm feeling of grillby's seed entering him and their souls bonding together, successfully making them soul-mates. They passed out, still connected to each other, into a deep sleep forever bound together as one…