Years passed. Brad (in David's body) grew up tall, hairy, and very physically fit.
David (in Brad's body) was short and ugly. In fact, he was one of the shortest and ugliest kids in his class. He was constantly astounded at how stupid his little-kid brain was, first as a 4-year-old, then as a 5-year-old, etc. He had brief moments where he remembered his old self, but they would quickly evaporate.
As he got older, David found that his new brain was sluggish and lazy, and so was his body. David started to look visibly chubby at age 6, and by the time he was 10 he was obese. He would look at himself in the mirror every shower, bouncing his big belly and breasts, not believing this was him. Brad's big ears and stupid face were the only reflection he would ever see.
The insults from others in his class were so childish, and yet, Brad's body and brain made him emotional enough to cry every time someone made fun of him.
David felt like Brad's body was a weird costume he was forced to wear. And yet, after all these years, it was growing taller and fatter and uglier while he was stuck inside it... The body, the "costume" he was stuck inside...
It began to feel like he could never take the costume off, as though he WERE Brad! The costume had to come off! Enough of this!
David, looking in the mirror, felt his face flush and redden and start sobbing. Oh, no, not the crying again! Brad's body, the "costume", always started crying when David thought about how he looked in it! The "costume" would cry until David went to bed and fell asleep and woke up in the morning again. The "costume" would then feel really hungry until David filled it up with breakfast, and snacks, and lunch, and then more snacks...
David had these brief moments when it felt like Brad's body was a "costume", but that feeling would subside as David still had to go to school and do homework and get yelled at by his parents. Meanwhile, the "costume" got fatter and fatter...