"When the hell did you learn how to draw?"
Tony was having trouble not squirming under Steve's brush, and he took mercy on him and took a break to answer Tony's question.
"When I wasn't getting beaten up in every park and alley in Brooklyn," Steve said matter-of-factly, twirling the brush in the pot of chocolate and hovering above the masterpiece he was crafting on Tony's abdomen. The spreading branches of the oak tree were splayed over his ribs and down onto his hips, and the trunk had descended to a very ticklish and highly hopeful spot right above Tony's cock. Steve's brush came down and began to decorate the smooth skin with the elegant twists of the roots.
"You're killing me," Tony groaned, and leaned back to watch Steve work from the mirrored panels over his bed. "I was just, you know, expecting a little 'Property of Steve' or 'I'm with stupid,' or something."
Steve didn't answer, caught up in branching out the tendrils along Tony's length.
"Shoulda known you'd be a damn perfectionist. Why the tree anyway?"
Steve was having a hard time hiding his grin. Every other word Tony said was accompanied by a faint groan or choked-off gasp, his hands clutched in the sheets to stop himself from messing up Steve's work.
"Because it's a challenge. Trees are hard for me," Steve said. He dipped his brush again and swirled it around the head of Tony's cock, the chocolate thinning as it mixed with his copious pre-come.
"I am very hard for you," Tony said through gritted teeth. His cock throbbed, and muscles stood out in Tony's neck as he held onto control with teeth and toenails.
"I know." Tony looked up as Steve slid the brush into his mouth and out again, now free of chocolate. He swallowed hard, shaking with holding back, his knuckles white on the sheets.
"JARVIS, get some close-ups, and fast!"
Steve moved before the sound died away from JARVIS' voice, mouth around Tony's cock, tongue tasting and reclaiming every delicious, lovingly-created line. Tony didn't last ten seconds, painting Steve's mouth white as he came, sweet chocolate balancing the taste of bitter seed.
Tony collapsed bonelessly into the bed, slack and easy, and Steve propped him up against his thighs, parting Tony's legs to get a close-up perspective of the art on Tony's body. In repose, the branches of the tree swayed in the play of muscle and the deeper, easier breathing.
"Gonna sign your masterpiece?" Tony asked, and spread himself just a little farther, a blissed-out smile on his face.
Steve smiled in return as he slid inside Tony's heat, his hands smearing the chocolate as he gripped Tony close. He thrust deep and slow, enjoying the destruction of his art as Tony went from lax, lust-addled, and passive, to joining in as his cock perked up again. The last few strokes had Tony nearly scoring him with his nails as he striped white across Steve's stomach, and Steve let go with a gasp, filling Tony up. It took another five minutes before either of them had the presence of mind to think of letting go.
"I'm going to get this into MOMA, I swear to God," Tony mumbled, stealing a half-conscious kiss before exhaustion dragged him under. Steve leaned over to grab a washcloth before the chocolate nailed them both to the sheets. He just knew Tony would do it too, probably in a private, by-appointment-only collection. Steve grinned as he wiped the last of the chocolate from Tony's body, leaving him a blank canvas, and picked up the brush again.