"Um... Eli?" asked Ty shyly.
"Yeah? Are you OK, Ty?" the handsome boy replied.
"Um... I've realised, I don't want you to be my brother," Ty blurted out. "You're really handsome and I'm attracted to you, and I... I think I wanna try switching sex like you did! I wanna be your girlfriend!"
To his relief, Eli was just as flattered as he had been by the first wish. "Aww, Ty!" he smiled. "That's so sweet of you! I just know you'll look really beautiful as a girl."
"Thanks," Ty mumbled as he locked the door and undressed, looking at himself in the mirror (and feeling Eli's eyes on him) as he wished to be transformed like Eli had been.
He felt an intense tingling sensation envelope his body, and odd sensations and desires and hormones seemed to race through him as the wish directed his body to change itself in a myriad of ways.
His skin seemed to smoothen all over as his muscles shrank and turned more lithe, his hands and feet noticeably more small than before. His figure seemed to convulse and recede inwards, his figure slimming and curves forming. His facial features softened, his cheeks rounder, lips puffier, neck narrower, the bulge of his larynx receding and his voice rising in pitch in response.
As the changes started to affect Ty's reproductive system, the sensations grew more intense and arousing. His nipples swelled and felt sensitive in a way he'd never felt before, and with each deep breath mounds of flesh swelled and grew on his chest until he had clearly sprouted soft breasts. He felt Eli's eyes on them and a mix of a shamed desire to cover them and a thrill of arousal at the boy seeing them came into his head. He felt his hips seem to flare outwards and looked past his new boobs to see his penis and testicles, which felt more sensitive than ever. The shaft started to shrivel away and the balls tugged up inside him- and all of a sudden 'him' felt like a very foreign word to Tyra, as she realised was her name now. She felt what had moved inside her reshape as it moved upwards and form into her ovaries, while the emptied sac in her crotch flattened to a small mound, the penis continuing to turn more sensitive and small. Eventually she felt it all come together- a womb and ovaries finished forming inside her, the nub that had been his penis finished reforming into her clitoris, and an opening formed between her legs, giving her a vagina.
Tyra turned to look at Eli, winked and gestured for him to come over. He eagerly did and she kissed him passionately, feeling the large thick cock between his legs press against her stomach. Her body and mind burned with arousal at the sensation, and she felt herself instinctively respond- her nipples and clitoris grew hard and vaginal juices started to accumulate at her entrance.
Eli led her to the bed and carefully pushed her down, getting atop her and positioning himself to push inside her. Tyra held his hands tightly as Eli thrusted into her warm pussy, and groaned and panted at how her body stretched around him, relieved he held as still as he could and held her hands to try and put her at least a little at ease.
As one might imagine, having only been in these sexes for a few minutes each, instinct quickly took precedent over all else. Eli started thrusting eagerly and disjointedly, his body desperate to fill Tyra's with its seed, and Tyra moaned in her feminine tones as her pussy clenched around Eli's cock, her body desperate to make sure he didn't leave it without filling her with his essence. Neither wanted to pull away, focused only on reaching their peaks of pleasure and fulfilling their most primal biological drive.
Pretty much the only conscious thoughts the two of them could muster were amazement at the difference in feelings- Eli felt a newfound understanding of why men were always so desperate to get off, transfixed by the odd sense of strength he felt from this fucking, and Tyra felt amazed at how good it felt to be a woman right now, how much more sensitive her body was and how much more sensitive everything seemed taking this role in sex.
In amongst his hot groans and pants, Tyra heard Eli murmur, "I- I'm gonna-", and realized she was coming to her own climax. Almost in tandem they both hit their peaks and orgasmed, clinging to each other as Eli's cock painted Tyra with his semen, and Tyra's pussy milked Eli as hard as she could. They kissed each other softly as they slowly came down from the high.