FOR JUST A WHILE I step down into the pool. The water is bathwater warm but feels cool compared to the blisteringly hot air. Kick. Gliiiiiiide. Stroke. Gliiiiiiide. Side to side and back again. Dive under the surface.

Soar to the top. Arch my back. Flip. Flop. As soon as I slip into the pool, I am weightless. Limitless. For just a while. NAME-CALLING Eliana Elizabeth Montgomery-Hofstein.

That''s my name. My bestie, Viv, and my parents call me Ellie or El. But most people call me Splash or some synonym for whale . Cannonball into a pool, drenching everyone, and wear a whale swimsuit to your Under the Sea birthday party when you''re a chubby kid who grows up to be a fat tween and no one will ever let you live it down. Ever. SPLASH IS BORN Now, whenever I swim, I use the steps to ease into the water, careful not to make waves, because the memory of my pool party plays in my head like a video on a loop. It was my fifth birthday. I wanted to be the first one in, so I ran to the edge and leapt into the air and tucked my knees into my chest.

Water sprayed up as I sank down. I bobbed to the surface, expecting cheers for the splashiest cannonball ever. That didn''t happen. "Splash spawned a tsunami!" my sister, Anaïs, shouted. "She almost emptied the pool," my brother, Liam, chimed in. I dove under, drowning my tears. I wish I could tell everyone how they made me feel that day-- humiliated, angry, deeply sad. But every time I try to stand up for myself, the words get stuck in my throat like a giant glob of peanut butter.

Besides, if they even listened, they''d just snap back, "If you don''t like being teased, lose weight." FAT GIRL RULES Some girls my age fill diaries with dreams and private thoughts. Mine has a list of Fat Girl Rules. You find out what these unspoken rules are when you break them-- and suffer the consequences. Fat Girl Rules I learned at five: No cannonballs. No splashing. No making waves. You don''t deserve to be seen or heard, to take up room, to be noticed.

Make yourself small. WHAT, WHY, WHO, HOW, WHEN The first Fat Girl Rule you learn hurts the most, a startling, scorpion-stinging soul slap. Something''s changed, but you don''t know what. You replay the moment in your mind from every possible angle, trying to understand why. Why the rules exist and who. Who came up with them and how. How does anyone have the right to tell you how to live just because of your weight? Mostly, you remember the smack of the change. One minute you were like everybody else, playing around, enjoying life, and then, with the flip of an unseen cosmic switch, you''re the fat girl, stumbling, trying to regain your balance.

Acting as if you know what you''re doing, like when you used to play dress-up and tried to walk in high-heeled shoes. THE GIFT Every time I see a pudgy preschooler, I want to hand her my list, like the answer sheet for a test, to spare her the pain of learning the rules firsthand. But instead, I give each girl the gift of more days, weeks, and months of a normal life. Whatever that is. BELLIES DANCING Viv''s mom caught her dad with another woman and said Texas wasn''t big enough for the three of them. So now my best friend has to move to Indiana. In my backyard, we livestream the Latin Music Festival on an outdoor screen as part of her going-away party. Viv starts belly dancing like she learned in a class at the Dallas Public Library, where her mom was a librarian.

I follow her lead and our arms morph into snakes as our hips figure-eight. My dog, Gigi, a pug, runs circles around us as we sing at the top of our lungs along with the bands and dance with complete abandon, like you do when you''re alone in your room trying out some new moves or making up some of your own. Except it turns out we''re not alone. THE NEW NEIGHBOR Mid-twirl, I open my eyes to see a girl''s head pop up over the fence, then disappear and reappear. This trampoline girl saw me shake parts of me I didn''t even know I had. "What do you think you''re doing?" I stop dancing so fast I about give myself whiplash. I see her head again. "IheardDíasDivertidos.

" She says it so quickly it''s like one word. She disappears and reappears. "Couldn''thelpmyself." In a flash, she climbs over the fence and lands in front of me. "I''m Catalina Rodriguez." A POET AND A MUSICIAN Catalina points to the concert on the screen. "Wow! So you like Días Divertidos, too? I have all their songs on my playlist." "Me too," I say.

"Who else do you listen to?" "Don''t get Ellie started." Viv rolls her eyes. If eye-rolling were an Olympic sport, she''d be a gold medalist. "I''m a poet, so I love music because lyrics are sung poems," I say. "Rap and country are my faves." "I''m a guitarist," Catalina says. "I like all music but love Latin." She chooses her words carefully, like me.

But she''s not like me. Catalina''s skinny like a pancake. I''m more like a three-tiered cake. My fatdar should be sounding the alarm. Why isn''t it? THE THING ABOUT FATDAR Fatdar is a lot like Spider-Man''s Spidey sense, a sixth sense. Somehow we just know when someone''s about to say something hurtful or do something mean. Even in a crowd, I can spot a fatphobe, someone who''s grossed out by overweight people. Fatphobes give off this vibe.

Part discomfort. Part shock. Part fear. Part anger. And all hatred. SHADOWS " ''Baila conmigo''!" Catalina shouts as the next song starts and she dances with us. "Teach me that one move, Ellie," she says. "Which one?" "The one where you were kinda kicking your leg while you spun.

" When I dance knowing Catalina''s watching, I feel every pound of my legs, see my fat shake, and notice how round my shadow on the grass is next to her angles, so I stop. Fat Girl Rule: Move slowly so your fat doesn''t jiggle, drawing attention to your body. But that uncomfortable-in-my-own-skin feeling fades as the music blares and Catalina squeal-screams, going all bananas with us, during the tribute to Selena. If dance partners were food, Catalina and I would be peanut butter and jelly. Cookies and milk. Chips and salsa. We''re different, but make a perfect combo, heads, hips, and hands moving in sync. Right on cue as the sun sets, the katydids start their singing, fast and furious since their tempo''s based on heat or maybe Selena''s bidi-bidi-bom-bom beat.

"Catalina, dale las buenas noches y ven a casa," a woman''s voice calls out. "Gotta go," Catalina tells us. "Thanks for letting me crash your party." She climbs back over the fence, then trampolines. "Can''twaittocomeoveragain.".