A/N: This story is a collaboration with the-clarity-organism

To the amateur, the difference between late spring and early summer remained faint and ethereal, as fleeting and temperamental as fog over a riverbank. But the climate was a part of nature, and nature was a part of science. Science was a part of math, and math was deterministic, predictable, and discrete.

There was a precise difference between late spring and early summer, and Metal knew exactly where that it was. It was just outside Sonic's front window. It was in the drooping of apple blossoms and in the way the dry grass stood upright, stiff, and harried.

While the day's heat was nearly oppressive, the early evening brought with it a light coolness, and so Metal opened the window as wide as he could, letting in the damp, freshly cool air.

"Sonic? You are not too hot, are you?" Metal asked.

"Hm?" Sonic glanced over to the window. He smirked, running a hand through his fluffy, werehog quills. "Well, in a way—"

A small fit of laughter cut off the rest of his sentence. "No, don't worry. I'm alright, Mets. You?"

"Please. Do you know how hot the average CPU can get? I am utterly fine."

Sonic was sitting at their kitchen table. It was made of faded oak planks tacked together with nails as long as Metal's fingers. They had made it themselves, one of the first projects they had ever done together.

Metal took a seat across from Sonic. "Are you not hot in your nocturnal form's fur? I know the night is shorter in the summer, but the air is much warmer."

"Eh, I got used to it after a while." Sonic shrugged. "Besides, it's not as hot as it looks."

He sat up from the table then walked over to the couch. He plopped down lazily, kicking his feet up and reclining. He grinned, patting the seat next to him.

"I see." Metal followed Sonic and took the seat next to him. "You are certain you are not too warm?"

Sonic rolled his eyes, then he wrapped an arm around Metal. "You worry about me too much. I'm fine."

Sonic smiled. He leaned in and lightly kissed Metal's cheek. "Thanks though."

Metal rubbed his cheek gingerly. Even after all these months, every time Sonic did that, it still made him feel slightly dizzy.

"Ah, wait! I know what would make things cooler!" With a tinge of regret, Metal slid out of Sonic's arm and off the couch. He marched over to the window on the other side of the room "If we can get a cross draft, that would make the cooling effect more optimal. I will just…"

Metal trailed off. Even in the dim evening light, the horizon had grown dark with a thick layer of clouds.

Sonic chuckled. "I told you I was fine, Mets. You sure you didn't just wanna be away from me that badly?"

Metal heard Sonic, and yet a response didn't seem to come. Instead, he could only stare out at those darkening clouds. They were low enough that they appeared to roll toward them.

"...Metal?" There was a shifting sound behind Metal as Sonic pulled himself off the couch.

Footsteps approached Metal. The familiar warmth of Sonic's hand touched his shoulder. "Hey. What's up?"

Metal's gaze was glued to the window. He whispered, "The weather changes so quickly sometimes. It can be impossible to predict."

Sonic followed Metal's gaze out the window. "Yeah?"

He walked closer to the window and leaned on the windowsill. "Well, on the bright side, you don't have to water the garden today."

"Do you know, Sonic," Metal's voice was even quieter, "what makes a machine and a biological creature different?"

Sonic looked back at Metal, eyeing him for a few extra seconds.

"Uh...I mean, I guess machines can be fixed up easier?"

"No. It is more fundamental than that." Metal didn't look away from the window. "Machines can only do what they are programmed to do. There is no other possibility. Machines are static."

He set his hand on the window. "But biological organisms can grow and evolve. Change is in their very nature."

One of Sonic's hands was still on the windowsill, but Sonic placed his other over Metal's hand. "But you're not doing what you were programmed to."

Metal glanced at their hands. His gaze drifted back to the window. "Are you certain of that? Or did the doctor just program me with enough room for error that I can do this? If the latter were true, I am not technically acting with my own agency."

Sonic's expression turned borderline offended. "...Mets, I don't think I'd fall in love with some robot who just stumbled into following some weird command. You're way too complex."

Tilting his head just slightly, Metal met Sonic's gaze. "Complex? Entropy is also complex, but we do not consider randomness to be growth. No, there is a fundamental difference. Growth implies intention. That is the difference I think. It is change with direction, a constant need to improve oneself."

Metal turned, placing his hand on top of Sonic's. "You nocturnal form is an example of that. You have used your agency to improve yourself in this form. Think of all the fighting strategies you developed yourself. That is what it means to change."

"But you've changed," Sonic argued. "Mets, you're overthinking things again. If you're just following some program, then why'd you make so many choices that wouldn't make sense for a robot? Eggman made you to kill me, but you changed. You broke away from him and joined me. We got together because that's what we both wanted. You changed from being just one of Eggman's robots to being the smartest guy I know."

He chuckled. "Even if you're a little crazy when it comes to thinking about yourself."

He took Metal's hand gently in his own. "Are you really gonna tell me that all this is fake? That this isn't all you enjoying this?"

Sonic had held Metal's hand like this before. The times were nearly countless, and yet Metal remembered them all. It wasn't just the context that gave them variety. It was the way Sonic looked at him, the way Sonic smiled.

It was like that now too. The light wind of the open window gently ruffled Sonic's fur, and the pale, yellow light of early evening made Sonic's eyes appear brilliant and earnest.

"I do enjoy this." Metal gently squeezed Sonic's hand. "I enjoy it more than anyone could imagine."

"Then there's no need to worry about some program or if there's something controlling you."

Sonic brought his hands up to Metal's shoulders, squeezing them reassuringly. He even knelt down to be closer to Metal's level. "You're not following anything except what you really want. You wanted to get away from Eggman, and you wanted to be with me."

He smirked. "Which means you have great taste, by the way. You can't program great taste."

Sonic shook his head, getting back on track. "What I mean is—Mets, you changed for the better. Yeah, I know it's not like me or nature where it's easier to see, but I can see it and you know I'd never lie to you."

Metal thought about these words, carefully flipping each one through his processors. It was true what Sonic said—Metal had wanted nothing more than to be free from the doctor. And now—

Now he wanted nothing more than to be with Sonic.

"Sonic—" Metal leaned forward, placing his face against the thick fur coating Sonic's chest. "You have always been so kind to me. I owe you so much."

"I owe you a lot too," Sonic whispered, running his hand along the armor of Metal's back. "You gave me all the credit for dealing with this, but you were there too, remember? You were there for me."

Metal slid his hands through Sonic's fur, brushing through the thick strands to come closer to Sonic's skin. He tilted his head just slightly, turning his face to look up at Sonic. "Then we have both changed. In a way, we changed with each other."

"Mhm." Sonic smiled. "And I'm embracing the change."

Then he stood up and pulled Metal into a hug.

The pun made Metal groan, and yet all Sonic's fur and muscle cut off most of the noise. At that point, there wasn't much left for Metal to do but sink into Sonic's fur. So he did just that, wrapping his arms around Sonic's chest and pressing his face against Sonic's arm.

"Perhaps embracing change is for the best."

Sonic chuckled, nuzzling Metal lovingly. "Yeah, but I wouldn't say no to a kiss either."

Metal lifted his head just enough to slide it over Sonic's shoulder. "Well if you must be so insistent."

He then slid his head forward, connecting his muzzle to Sonic's lips.

Sonic let out a soft hum of contentment as he kissed Metal back. As usual, there was no hesitation, only the strong yet gentle love that Sonic felt for him.

That was one thing Metal hoped would never change, and he didn't need Sonic to tell him to know it never would.