She is like some marvelous water bug, all legs, and she skims over the surface of the court with a lightness that seems almost comical. She is 17 and she wears white beads in her hair and when she thanks Jehovah God after each fresh win, she smiles like … and there was light. It’s 1999 and Serena Williams is about to win her first U.S. Open, her first major tennis tournament. But she plays like she’s still figuring out her own body. To her opponents, she is a phenomenon of power — she has a serve like a boulder shearing down a ski slope, and with roughly the same effect on European blondes — but watching her now, 16 years later, what strikes you is that gangly, playful, slightly uncertain lightness. She smacks off-balance bullwhip forehands in midair. She hits bloopy lob winners from 4 feet behind the baseline. Against Monica Seles in the ’99 quarterfinals, she keeps getting caught in slightly awkward backhand positions, and to compensate she flicks one leg up behind her like she’s playing hopscotch. And in a way she might as well be.

To reach the final, she plows through Kim Clijsters (just 16 but a future four-time major winner), Conchita Martínez (a former Wimbledon champion), Seles (a nine-time major winner), and Lindsay Davenport (the defending champ and an eventual three-time major winner). In the final, she tosses aside world no. 1 and five-time major champion Martina Hingis in straight sets, 6-3, 7-6(4), and there’s an element of revenge here, because Hingis has both taken shots at the Williams family in the press, saying the father, Richard, has a “big mouth,” and beaten Serena’s sister Venus in the semifinals. But in her victory speech, Serena doesn’t seem angry or self-consciously triumphant. She’s artless, radiant. She thanks her parents, her sisters, the crowd — standard stuff — but the look on her face is like: springtime.

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It’s a little hard to watch this now, even, because you’re thinking of everything that’s ahead of her — the hostility from fans, the overt and subtle racism, the fallout from her own on-court freak-outs, the moral hauteur of the media. She’s seen glimmers of all that already, in the sniping from Hingis, in the way Venus has been treated,¹ but here, she’s not thinking about it. Here, she’s a kid who’s finally made it to the place where she knows she belongs, and she’s looking to the crowd to ratify the moment for her; she’s inviting it to accept her. She’s trusting in a way that kind of breaks your heart. Everything is so new. At one point the announcer has to tell her which way to look to have her picture taken. She makes big eyes at the winners’ check, and they hand her the trophy, and she cries a little. That’s how it starts.

♦♦♦

I’ve been thinking about Serena as a kid because I’ve just been watching Serena as an adult, as the 33-year-old who just won her 20th — 20th! — major title at the French Open, beating Lucie Safarova 6-3, 6-7(2), 6-2 in the final. She’s nearly half her life removed from that first win in Flushing. (Think about that for a second; think about how astonishing that is.) During her run at Roland Garros, she wasn’t light or uncertain. She was exhausted and clinical, struggling through a flu that left her, in her semifinal match against Timea Bacsinszky, hunched over and panting on her racket. When she saw an opening, she annihilated the ball, and when she didn’t see one, when a drop shot looked a little too far away or an angle a little too acute, she let the point go. It was, in other words, a win enabled by supreme experience, a master class in high-stakes resource management by a player who’s won 20 of her 24 Grand Slam tournament finals and who’s lost only once since November. And when she took the microphone after the final, she didn’t stammer or blink. She addressed the crowd in confident French, a worldly, sophisticated woman who spends much of each year in Paris.

It’s so rare, in tennis, to watch a player really grow up. I don’t mean “mellow out” or “stop partying” or whatever grow up usually means in sports; I mean develop a fully adult self, distinct from the kind of prolonged high-stress adolescence that most stars, for obvious reasons, inhabit throughout their twenties. To succeed in professional tennis, players have to keep obsessively honing a set of skills that they’ve been perfecting since childhood, and they have to live at the center of a network of coaches, trainers, and PR reps whose livelihoods they control. It’s no wonder that a certain frozenness tends to accompany all of this, that players can sometimes seem like a strange cross between the CEOs of medium-size companies and high school students on a never-ending trip.

The easiest thing to do with Serena’s incredible late-career dominance is to describe her as a force of nature, something irresistible and transcendent. She’s a supernova, an atom bomb. I do this all the time myself, and it’s not even inaccurate, because Serena is that good. You run the risk, though, of turning her into a sort of impersonal pulse of destruction, which is a weird thing to do, because there has seldom been a tennis player who was as compelling a personal presence as Serena. When she’s needy, angry, amused, disdainful, awkward, whatever she’s being in the moment — well, there’s always a person there who’s more obviously complex, more textured, than most of what shows up on TV. Serena has layers. And looking at her and going “SKYNET QUEEN FLAMETHROWER” has the strange effect of obscuring the fact that watching her grow up has been one of the signal experiences of 21st-century tennis.

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Careers are short in this game. Agassi had a distinctive late period. Federer is having one. Who else? It’s a short list, and if you ask who else has had a distinctive late period while dominating the sport to a greater degree than they did in their earlier period, it’s an empty one. Consider: When the Williams sisters first arrived on the scene, they caused a panic because they broke the flow of women’s tennis. The WTA was an orderly universe, a continuity where change happened according to a set cadence: first Chris and Martina, then Steffi and Monica, etc. Then the Williamses arrived, and it wasn’t. Suddenly legacies were being cut short — Hingis, who declared in a not-all-that-passive-aggressive-for-her-runner-up-speech at the ’99 U.S. Open that she expected to face Serena in many Grand Slam finals to come, never won another major. And the revolution was being imposed from what felt like the outside, by players who looked and acted nothing like the (say it: white) norm. Now, though? Serena is admired because she’s become the order of women’s tennis, virtually by herself.² She’s the player whose gravity holds everything together — but there, see, I’m doing it again.

What’s she like as an adult? She’s changed, I guess, in the ways you’d expect. She’s been both chastened and confirmed by the world in ways that most of us can only imagine. She’s lost a half-sister in a shooting. She’s nearly died herself. She’s been booed and called names. She’s been ripped by the media for a thousand nothings (Crip walking on TV after winning an Olympic gold medal) and a few somethings (quasi-blaming the victim in the Steubenville rape case). And then, she’s heard her name chanted in her sport’s biggest stadiums. She’s seen her face in lights on multiple continents. She’s made millions of dollars. Oh, and she’s won 20 majors.

She’s not sad, but she’s a little sadder. She’s less trusting, as you would be too. She still has that blazing smile, but what you see from her now more often is a serious, faraway look: chin up, narrowed eyes, like someone gazing out at a distant mountain. It’s a look of conscious dignity, of marshaling inner strength, and it tends to spell the end for her opponents. It’s the look she put on during the rest break after she dropped the second set to Safarova. She was broken once more to start the third set. Then she won six straight games to finish it.

If this sounds mythologizing, I don’t really mean it to: She’s also still the goof who Instagrams endless dog snapshots and selfies with her BFF Caroline Wozniacki. She’s 33, not Queen Victoria, and she’s as conscious of her own brand as a top-level global athlete in 2015 has to be. Still. She goes somewhere in moments of duress. It’s written on her face. And wherever that place is, it’s as far away from that kid in Flushing as are the French victory speech, the apartment in Paris. I don’t know where she found that, I really don’t. In its own way, it’s as stirring as any of her forehands.

Here’s what hits me the hardest, and what most completely undermines the Serena the Destroyer cliché. When she faces the crowd after a major win now, her look still has a hint of 1999 in it. That openness. That invitation to share in her moment. It’s a warier thing now, and more carefully managed; she lets herself go, but not completely. But it’s there. I think more and more that Serena always wanted to be embraced, not so much for its own sake as to confirm her place in tennis. As a kid, she knew she belonged to the game. The unfair lesson she’s learned as an adult is that she had to make the game belong to her before everyone would accept that she did.

1. Remember, Serena won the first of the Williams sisters’ majors, but Venus had broken through earlier, was far more famous, and took most of the first-wave backlash against whatever scary thing the Williamses were supposed to represent.

2. Does Sharapova count here? Seriously, tell me.