What do we really know about Tadzio? The truth is, not much. Without any access to the inner-workings of Tadzio's mind, his existence in Death in Venice is pretty much equivalent to the way Aschenbach sees him: as a living statute, an "exquisite work of nature" (3.55). When you think Tadzio, then, think eye candy.
Just because he's easy on Aschenbach's eyes, though, doesn't mean Tadzio's beauty is a simple matter. At fourteen-years-old, he is somewhere between being a child—with his golden locks and sailor suit—and a man. Britney Spears break, anyone?
Similarly, Aschenbach's infatuation with Tadzio seems to waver between admiring his beauty and desiring him as a sexual being. We might call this Tadzio's erotic power, which is not so much a force he willfully exerts on others, as his happenstance ability to inspire erotic thoughts in others. In fact, Tadzio is compared to Eros (3.51)—the Greek god of love, and origin of the word erotic—a figure who alternately appears as a man and as a child, and was believed to be an inspirer of love.
In this scene, for instance, Tadzio is described emerging from the ocean in a way that captures both his barely-there adolescence and his godlike power to inspire Aschenbach's eroticism:
But already he seemed a cause for concern; already women's voices were calling out to him from the cabanas, once more shouting the name that dominated the beach almost like a catchword, its soft consonants and long-drawn-out final u making it at once sweet and wild: "Tadziu! Tadziu!" Back he came, running through the waves, his legs beating the resistant water into foam, his head flung back, and to see so vibrant a figure, with the grace and austerity of early manhood, locks dripping, fair as a gentle god, emerging from the depths of sea and sky, escaping the watery element—it was enough to inspire mythical associations, like the lay of a bard about times primeval, about the origin of form and the birth of the gods. His eyes closed, Aschenbach harkened to the chant welling up within him and thought again that being here was good and he would stay. (3.60)
With the "women's voices" calling out to him in concern, but in a way that is both "sweet and wild"—thereby foreshadowing the orgiastic revelers in Aschenbach's stranger god dream (check out the "Symbols" section for more on this)—Tadzio appears to Aschenbach no longer as an innocent child, but "vibrant," in a state of "early manhood," "fair as a gentle god." And when he does, Tadzio himself foreshadows the "stranger god," who emerges from "primeval" times to give a voice to the "chant welling up within [Aschenbach]."
The tension is palpable, right? And in Tadzio, the ideal of statuesque beauty, there is already the spirit of erotic madness that will later infect Aschenbach.
Tadzio is a vision of beauty, but he's also (at least, for Aschenbach) an erotic symbol. But what does Tadzio think about all this? Let's check it out. At the end of Chapter 4, Tadzio smiles at Aschenbach, which moves Aschenbach so much that he finally confesses to himself that he loves the boy. Here, it seems like Tadzio notices the attention he's getting from Aschenbach, and reacts positively. Take a look at the way the smile is described:
Tadzio smiled, smiled at him, with an effusive, intimate, charming, unabashed smile, his lips opening slowly. It was the smile of Narcissus bending over the water mirror, the deep, enchanted, protracted smile with which he stretched out his arms to the reflection of his own beauty, an ever so slightly contorted smile—contorted by the hopelessness of his endeavor to kiss the lovely lips of his shadow—and coquettish, inquisitive and mildly pained, beguiled and beguiling. (4.19)
Here, the narrator clearly portrays Tadzio's smile as one that Aschenbach only falsely believes is for him. Actually, Tadzio is smiling at himself, the appearance of his own beauty in the world—much like the myth of Narcissus, referenced here, about a young male deity who becomes transfixed by his own beautiful reflection in the water.
In other words, no dice, Aschenbach. Tadzio only has eyes for himself.
The depiction of Tadzio's narcissistic smile adds to our sense that he is drawn into himself, existing in the story only as the beautiful form that Aschenbach worships, and ultimately, dies for. The only sign of his mind's inner workings is his "slightly contorted" smile, which belies his "hopeless" infatuation with himself. If nothing else, this should make clear that Tadzio is not in love with Aschenbach, and that instead he sees himself as an object of adoration, rather than as a agent of loving.
Which this brings us to one final note about Tadzio: his "sickly" appearance. Yep, though a good-looking boy, Tadzio, as Aschenbach notes early on, seems to be suffering from a mortal illness (3.62). Even as he becomes a symbol of beauty incarnate, the sign of death is still visible on his face, much in the way his smile betrays "hopelessness" and appears "mildly pained," and "contorted." Tadzio is both of this world and not, a living being and one, much like Aschenbach himself, who is already condemned to die. Intrinsic to beauty, then, is its end.
Kind of makes you look at Justin Bieber a little differently now, doesn't it?