Imagine Alfred Jr. travelling back in time when he's still a kid himself. He latches onto a teenage Damian immediately, since he's a familiar enough face. At first, his entire family teases him for being imprinted on like a baby duckling with its mom, but then their panic starts to grow when it becomes obvious that Alfred Jr. is fully treating Damian like his parent, which is crazy because he's still the baby of the family himself, there's no way he's capable of caring for a kid.
Bruce and the older batkids try and coax him away from Damian but they only succeed for a few hours at most before he starts wanting to go back to Damian. He also has intense separation anxiety (which is understandable considering how he got here) but it's really messing up Damian's schedule and overwhelming him completely. Jon appears at the Manor during a particularly bad spike of Damian's own anxiety and manages to handle the kid better than almost any of the other Bats.
By the time the Jon of the future arrives to collect his kid, everyone has already realised who he belongs to.
This made me write a short scene. It’s not really good, but I had fun okay? XD
"Oh, that’s so cute," Dick said, amused, when he spotted his youngest brother on the living room couch. Alfi was lying on his stomach next to Damian, sprawled across the space with his bare feet pointing toward the teenager. The young Wayne looked up from his laptop and shot him a dark look. "Jon is back from the park, he completely wore him out."
Dick nodded and sat down beside the two of them, with gentle fingers, he brushed a few strands of hair out of the child's eyes. "You seem stressed," he remarked without looking up. Damian remained silent for a long moment, only the long sigh that escaped him proved Dick was right.
"Jon said the child called him Dad..." He admitted quietly. "Repeatedly."
The older man's hand stopped where it rested against the boy's head. "Sorry?"
Damian let out a small, panicked laugh. "Yeah, crazy right?"
Dick's mouth was slightly open, he blinked. "He was probably just confused—"
But he stopped himself as he looked a little bit closer at the child's face. Oh. "I mean...he does look a little bit like—"
"Like Jon", Damian interrupted him. "He looks exactly like Jonathan. But father did a DNA test, he is definitely mine i—", the teen leaned back, covering his eyes with both hands. "This is bad..."
Dick let out a laugh in disbelief. "You and Jon?"
"Seems like it", Damian responded dryly.
"But...how? You are both men", Dick said in disbelief.
Damian lowered his hands enough to glare at him. "I wasn't aware, thank you for your groundbreaking observation, Grayson"
Dick ignored the sarcasm. "I mean... maybe it's just a coincidence that he looks so much like Jon... and...maybe the two of you raised a child together for some platonic reason—that wouldn't be the strangest thing that could happen."
Damian raised both eyebrows at him.
Dick sighed deeply. "Or Kryptonians can get men pregnant too..."
Damian's eyes widened "or they can get pregnant!"
Dick chuckled, "or that way around. Whatever helps you sleep at night, D."
Damian, dramatic as ever, looked like he wanted to die. "This isn't funny, Grayson" he hissed.
The older brother raised both hands in a conciliatory gesture, but he was still smirked stupidly. "Alright, alright, I'm sorry."
He slowly lowered his arms, his gaze settling back on the child. "Look, there could be all sorts of explanations..." He raised his eyes to Damian. "Just...would it really be that bad? If he was Jon's?"
The younger one looked as if Dick had grown a second head. "Yes, that would be horrible!"
"Why?" Dick asked softly.
Damian was struggling to find the right words for a moment. Because now that he had to think of a reason...there really wasn't a good one. "Because... because he is my best friend and...that would just be weird as fuck!"
Dick sighed. "It being weird for you right now is not really a reason though..."
Damian clenched his jaw, his gaze dropping down to the kid that was still sleeping peacefully beside him. Sleeping like a damn stone huh?
The longer Damian looked at him, something caught his eye. One of Alfi's ears was a bit pointy, nothing you would notice on a first look...but it was there. Damian swallowed thickly. It was this small imperfection that Jon had as well...he got it from Clark. It wasn't anything kryptonian...just a little gene defect. Kon had it as well... stupid pointy ear.
"I guess...the child seems fine right? Healthy and..." Damian looked at his oldest brother anxiously. "He hadn't shown any concerning behavior, had he?"
Dick's face softened. "He is completely normal, Dames."
The teen took a shaky breath. "And Jon is very reliable... he would make a good father. That doesn't mean I have to like this possible future, but... he would do a good job, and I trust him... that's all that matters."
Him and Jon? Someday? In a far far future? Impossible.
Some kind of unwanted cloning experiment? Maybe...
But whatever the answer was... it couldn't be that bad. After all, sitting right here was the proof. A child who—to Damian—was already perfect.