Link is the quintessential silent protagonist, and on top of that, there are variations on canon (such as the manga vs the games). In addition, while there are some traits that are core for every iteration of Link, there's plenty of room for differing interpretations of his personality. For my portrayal of Link, I draw almost entirely from the games (including his appearance in Twilight Princess), and here are the reasons for the approach I take to him:
A major theme I play with Link in games is centered on a feeling of not belonging anywhere. In TP, the Hero's Shade lingers on as a spirit instead of passing on due to regrets of not passing on his skills... and that he was never remembered as a hero. While this is past the canon point I'm pulling Link from, it's relevant to my interpretation, since it's his canonical future. Personally, I don't think it's the fame or glory the Hero's Shade is missing, or even just plain old recognition — It's what that means for him when placed in the context of the rest of his experiences.
From childhood, Link never felt like he belonged — Among the Kokiri, he was the only one without a fairy. While one Kokiri picked on him for it, the others were very friendly and nice to him... But he was still never truly one of them. He was still an outsider. Then, when his body was aged to an adult, his friends didn't recognize him, and he learned he was actually a Hylian, further proving that he didn't belong in the forest. But he grew up isolated from other Hylians, and was an outsider to them, too — He didn't know their culture, and stood out with his Kokiri clothing and fairy.
Then you add in the fact that, because he was sent back to the Child Timeline at the end of OoT, no one knew of what he had done — and, more importantly, what he had gone through. The people he had made friends with had no memory of the things that happened in the other timeline, so those friendships didn't exist for them. These things would all be isolating enough, but then in Termina, similar issues cropped up as Link had to reset the same three days again and again, with only Tatl remembering everything that transpired with him.
For the Hero's Shade, this means that by not being remembered as a hero, he shouldered the burden of his experiences alone, leading to him keeping to himself, initially just emotionally, but then eventually expanding to include his skills, as well — The abilities he learned over the course of these alienating experiences. It's not about his accomplishments being lost to history — He doesn't know that the story of the Hero of Time echoes throughout the rest of the series, but he didn't embark on his journeys for the rewards. It's about his suffering being lost to those around him when he was alive, and the effect that had on him as a person. Talking about your trauma is difficult enough without stacking on his quiet nature or the extraordinary circumstances of his adventures.
So let's take these issues all the way back to when he's still young, in the earliest stages of these problems — aka, my canon point. He doesn't yet have a grasp on how much these feelings will stay with him for the rest of his life, let alone how to begin processing any of it. Right now, because of everything he's been through, in many ways he's just a kid who had to grow up way too fast, and has forgotten by and large how to be a kid. Since the different iterations of Link are often spiritually similar simply by nature of their connection, as well as the thematic parallels between them, I take inspiration from Breath of the Wild's take on his silent protagonist role. All of that pressure, all of that isolation, and a lack of the opportunity to socialize and grow up in a non-traumatic way result in Link having a difficulty in expressing how he feels, adding to the impression that he's odd for his age. In my portrayal, his experiences have made him very mature and serious for being so young, and while he still has a very childish outlook on many things (such as a black and white view on morality, since his adventures did little to encourage a deeper understanding of such a complex subject), and is still capable of acting like a kid, these behaviors look out of place compared to his usual demeanor.
I do borrow one trait from the Majora's Mask manga, which is shown towards the beginning — Link dislikes being treated as a kid and looked down upon by adults. Given how the Kokiri react to adults (based on how they react to adult Link, who they don't recognize as their old friend and treat as a stranger), and given everything he's been through and the advanced skills he developed through those adventures, I believe that's an entirely justified reaction for him to have, so I adopt it into my canon. Link's experiences put him in a situation where he doesn't feel like a kid any more, but he isn't an adult, either... and he also doesn't really fit the "teenager" mold — He has a unique relationship with his age, and it's just one more thing that showcases (and exacerbates) his feeling of other-ness among other people.
notes on my interpretation
A major theme I play with Link in games is centered on a feeling of not belonging anywhere. In TP, the Hero's Shade lingers on as a spirit instead of passing on due to regrets of not passing on his skills... and that he was never remembered as a hero. While this is past the canon point I'm pulling Link from, it's relevant to my interpretation, since it's his canonical future. Personally, I don't think it's the fame or glory the Hero's Shade is missing, or even just plain old recognition — It's what that means for him when placed in the context of the rest of his experiences.
From childhood, Link never felt like he belonged — Among the Kokiri, he was the only one without a fairy. While one Kokiri picked on him for it, the others were very friendly and nice to him... But he was still never truly one of them. He was still an outsider. Then, when his body was aged to an adult, his friends didn't recognize him, and he learned he was actually a Hylian, further proving that he didn't belong in the forest. But he grew up isolated from other Hylians, and was an outsider to them, too — He didn't know their culture, and stood out with his Kokiri clothing and fairy.
Then you add in the fact that, because he was sent back to the Child Timeline at the end of OoT, no one knew of what he had done — and, more importantly, what he had gone through. The people he had made friends with had no memory of the things that happened in the other timeline, so those friendships didn't exist for them. These things would all be isolating enough, but then in Termina, similar issues cropped up as Link had to reset the same three days again and again, with only Tatl remembering everything that transpired with him.
For the Hero's Shade, this means that by not being remembered as a hero, he shouldered the burden of his experiences alone, leading to him keeping to himself, initially just emotionally, but then eventually expanding to include his skills, as well — The abilities he learned over the course of these alienating experiences. It's not about his accomplishments being lost to history — He doesn't know that the story of the Hero of Time echoes throughout the rest of the series, but he didn't embark on his journeys for the rewards. It's about his suffering being lost to those around him when he was alive, and the effect that had on him as a person. Talking about your trauma is difficult enough without stacking on his quiet nature or the extraordinary circumstances of his adventures.
So let's take these issues all the way back to when he's still young, in the earliest stages of these problems — aka, my canon point. He doesn't yet have a grasp on how much these feelings will stay with him for the rest of his life, let alone how to begin processing any of it. Right now, because of everything he's been through, in many ways he's just a kid who had to grow up way too fast, and has forgotten by and large how to be a kid. Since the different iterations of Link are often spiritually similar simply by nature of their connection, as well as the thematic parallels between them, I take inspiration from Breath of the Wild's take on his silent protagonist role. All of that pressure, all of that isolation, and a lack of the opportunity to socialize and grow up in a non-traumatic way result in Link having a difficulty in expressing how he feels, adding to the impression that he's odd for his age. In my portrayal, his experiences have made him very mature and serious for being so young, and while he still has a very childish outlook on many things (such as a black and white view on morality, since his adventures did little to encourage a deeper understanding of such a complex subject), and is still capable of acting like a kid, these behaviors look out of place compared to his usual demeanor.
I do borrow one trait from the Majora's Mask manga, which is shown towards the beginning — Link dislikes being treated as a kid and looked down upon by adults. Given how the Kokiri react to adults (based on how they react to adult Link, who they don't recognize as their old friend and treat as a stranger), and given everything he's been through and the advanced skills he developed through those adventures, I believe that's an entirely justified reaction for him to have, so I adopt it into my canon. Link's experiences put him in a situation where he doesn't feel like a kid any more, but he isn't an adult, either... and he also doesn't really fit the "teenager" mold — He has a unique relationship with his age, and it's just one more thing that showcases (and exacerbates) his feeling of other-ness among other people.