From what I've seen so far the fandom agrees that Atem is a cat nerd and when I thought about how he got his first kitty (I headcanon that he has two, but this is for another prompt, hihi), this little story came to my mind. ^_^

Tree

When he received Atem's call about half an hour ago, Seto knew from the strained tone of his voice and the hasty way he spoke that something was wrong and he didn't waste a second to leave his office and hurried to get him.

Upon arriving at the park next to the museum Atem was working at he couldn't see him though and looked around confused. He knew Atem loved walking through this park during his lunch break but he couldn't think of a reason why he would be here at this late time of day, when he should be working and especially why he called Seto out to join him here.

He turned his positioning system on and was confused when it guided him to the next tree.

"There you are!" He heard Atem's voice from above and when he looked up he spotted him sitting on a branch in the treetop, waving at him and smiling innocently. "My knight in shining armor has finally arrived to rescue me! What a delight!"

"Haha…" Seto looked up at him and crossed his arms over his chest, making his disapproval visible in that way. "What the hell are you doing up there?"

Atem opened his mouth when Seto saw a little kitty lying in his lap and after the initial pang of jealousy had vanished, he didn't need an answer to his question anymore and just held up his hand to silence Atem before he could even start to speak. He had seen Atem with cats so many times now, he knew how that usually ended and didn't need an explanation on how he got up there. "How many times have you tried this now and how many times have you failed?"

"And how many times have you tried to win against me and how many times have you failed?" Atem countered and Seto rolled his eyes.

"Tell me again why I shouldn't just walk away and let you rot up there?"

Atem raised an eyebrow and continued stroking the kitty's fur as if he hadn't done anything else his entire life. "You know the answer yourself."

Seto just grunted at that, checked the tree once more and started to climb up, while Atem let his feet dangle in the air and smiled affectionately at the cat that had started to purr. Seto glanced up and saw the way she stretched her little head out to Atem's hand to get more of his caresses and he tried hard not to hate her but he wasn't sure if that worked. "She seems to like you." He gritted out and continued his climb.

"I named her Mana." Seto opened his mouth to protest to he knew it was too late when Atem had named her already. He'd always known the day would come when Atem became a cat owner and obviously this day had finally arrived. "I've met her for quite some time now, gave her some food and talked to her, you know…" Seto rolled his eyes at that again, but didn't comment on Atem talking to the cat. Sometimes he didn't know if Atem wasn't a cat himself. He sure as hell had a lot in common with them. Last but not least his habit of climbing trees and then being unable to come back down alone. "She always seemed to wait for me, so when she wasn't here today, when I came out for lunch break and I went looking for her…"

"You spotted her in the tree and decided to help her..."

"But couldn't come down myself anymore." Atem finished and Seto made a noise in the back of his throat.

He stopped shortly afterwards though and looked at him confused. "Wait. You've been here since lunch break?"

Atem cleared his throat softly and his voice was just a murmur. "It was a late lunch break…" Even from the distance Seto could see the faint darkening of Atem's cheeks and he raised a mocking eyebrow.

"And your colleagues didn't come looking for you?"

"There hadn't been any tours today, so I was assigned to list the new artifacts" He paused a little and the color in his cheeks became more apparent. "They think I'm in the archive…"

Seto chuckled at Atem's small pout, shook his head and continued climbing up the tree until reached the branch next to Atem. He made sure he stood safe and then nodded to Atem, who gave him a small, relieved smile. Holding onto the kitty as if she would protect him and not the other way round, Atem slid closer to him but Seto frowned when he looked at the both of them.

"I can't take you both down at once."

"Oh…" Atem seemed surprised at first, but then his expression changed to something Seto couldn't identify. He let out a loud sigh, looked at the cat, back at Seto and to the cat again, that meowed softly as he picked her up and held her out to Seto in a theatrical way. "Please safe her, Seto! You're her last hope."

Seto blinked at him for a moment and then chuckled. "Are you serious?"

"I am." Atem said sternly and Seto was almost impressed by his acting skills when he got a little teary-eyed. He handed Seto the kitty and he tugged the small animal under a little protest in the pocket of his coat, glad he could hide his grin that way. Only when he felt Atem's fingertips at his cheek did he look back into his eyes. "I have just… one last wish."

"Yes?"

"Don't…" A dramatic pause. "Don't forget me, Seto."

Now he couldn't hold his laugh back anymore. As if he hadn't proved already that he was incapable of forgetting him! Still chuckling he leaned up a little and placed a kiss on Atem's hand. "Never."

Atem laughed a little, too but he cleared his throat quickly and put his pretend desperate face back into place. "Now go. And don't look back."

Seto nodded once, before shaking his head in amusement and then climbed back down, grinning brightly to himself.

When he reached the ground again he freed Mana from his pocket what caused her to meow loudly, and she loyally remained on the spot where he put her even as he turned and started to walk away from the tree altogether.

He didn't look back once, exactly like Atem had asked him to and just kept walking until his phone rang and Atem screamed at him. "Come back here and get me down, you jerk!"

Seto laughed loudly as he turned around and started to make his way back to the tree.

It was a blast to win against Atem.

Even if it was just a small victory like this one.