He wasn't sure exactly when or why the boy started imitating him; in fact, he hadn't even noticed it until Krillin had pointed it out.
Perhaps it started when the boy began crossing his arms when he stood.
Perhaps it started when the boy began sitting cross-legged beside him.
Or perhaps it started when the boy began wearing a white sweatband around his forehead.
But perhaps the most likely reason was that Piccolo didn't want to get attached to the boy and subconsciously ignored it.
Asking for a gi similar to his never really registered in his mind as anything other than relief he wouldn't have to see that ugly orange garb anymore. The boy sitting silently beside him in meditation was nothing more than blessed peace compared to his usual yammering.
But now, as they stood waiting for Vegeta's timer to run out, he noticed Krillin looking between the boy and the Namekian and finally began to put the pieces together himself.
And when Gohan walked away in shame, the monk looked straight into Piccolo's face and said, "Boy, does he love you!"
"Huh?" Piccolo asked rather stupidly, slapping himself mentally for it.
"He loves you," Krillin reiterated. "They say imitation is the sincerest form of flattery, and he is definitely imitating you!"
And so, as he lay dying, he realized he loved the boy too.
It didn't end there. In fact, Gohan began to act more and more like his mentor as he aged, and it was not going unnoticed by anyone. At any sort of social function the boy dragged him to, they were given a wide berth if they were together, which was about ninety percent of the time. The remaining ten percent was Gohan flitting around to exchange pleasantries, though his gaze continually darted back as if to make sure the Namekian didn't try to slip out without him.
But Piccolo didn't notice anymore. Gohan was just... Gohan. He was friendly with everyone, even Vegeta. The pair had lived alone together for a whole year. Of course they grew attached to one another. Of course they loved one another. But Gohan's love grew and extended to those around him, while his own had not.
But then, Goku, the most oblivious person Piccolo had ever met, said after an intense training session for the androids, "This is not fair! It's like I'm fighting two of you!" He pointed in mock-accusation at Piccolo. And Gohan practically beamed at the statement.
Oh yes, the boy had definitely begun imitating him again. But when?
Perhaps it was the day Piccolo had saved Gohan in the snow, who was in a cloak very much resembling his cape.
Perhaps it was all the times Gohan would come to him for another gi as he quickly began outgrowing his.
Or perhaps it had been just now, as Gohan not moments before attacked Goku without hesitation. He couldn't help the smirk that spread across his face or deny the warmth growing in his chest.
Then, something astonishing happened. Piccolo had been spending a lot of time with the Sons, and therefore by proxy the visitors that came by for progress check-ins. And he actually fully interacted with them, entering conversations.
And Goku again pointed out something he again had not noticed. Krillin and Yamcha had just left and Gohan was inside doing homework, whatever that was.
"It's really good to see you've loosened up, Piccolo! I guess spending all that time with Gohan must have rubbed off on you!" he joked. Piccolo's eyes widened and he stood stock-still. "Alright, I'm headed in for dinner. You want me to bring you a glass of water?" Piccolo shook his head woodenly, but Goku didn't notice the change in body language, obliviousness returning. "Alright, see you later then! Gohan will probably come out before he goes to bed, like usual."
Slowly, the shock recessed and he felt his cheeks burn in embarrassment. Goku noticed something he had never even thought of.
Was he imitating Gohan?
He supposed it was somewhat possible. Gohan was with him wherever he went. And in turn, he followed Gohan everywhere he went. And the boy was always happy. Maybe it happened then.
The final occurrence that negated any tiny, minute doubt anyone may have had (namely Gohan's mother) was the day Gohan requested a gi and cape exactly like his own.
And it had definitely happened by the time Gohan and Piccolo stood together with crossed arms, identical capes billowing in the wind as they looked out over Cell's arena.