One time I wrote a 256 word fanfic where Sebastian discovered Jim had a third nipple. This is that fanfic.
Sebastian had Jim pinned underneath him, leaving kisses and small bites at his collarbone. After leaving a nice little bruise at the base of his throat, Sebastian let his tongue trail down Jim’s chest and to a nipple, sucking and biting at that lightly as well.
Jim’s wrists were still pinned under Sebastian’s strong grip, and he writhed under the sniper as he kissed further down, but suddenly, Sebastian stopped. “I didn’t tell you to stop, Sebby! Did you fuckin’ hear me say stop?”
“Boss, there’s something near your rib,” Sebastian uttered as he sat up and let go of Jim’s wrists, looking puzzled.
“I didn’t ask for a medical exam, Seb! As I recall, you haven’t even removed my pants yet, lazy piece of—“
“Really, Jim, this doesn’t look good.” Sebastian leaned closer to take another look, raising an eyebrow and wrinkling his nose a bit. “Looks like a fucking mutated nipple or something.”
“Sebastian, if you are suggesting I have an extra nipple on the top of my ribs instead of holding me down and fucking me, I swear I will kill you right in our bed.”
“Jim, I’m serious, go look in a mirror.” Sebastian moved back again, sitting back on his heels, watching his boss stand up. Jim slid off the bed, exaggerating his movements to simply convey to Sebastian how irritated he was. Yet, he shuffled to a long mirror, investigating this ‘mutated nipple or something.’
“Fuck, Seb,” he gaped, glancing back at his sniper, “I do believe you’re right.”