Lexie was shocked at first, but didn't fight it. (As if she could, she was still incapable of doing so much as un clipping the 5-point harness with those mittens. "Um... I need to use the bathroom before we go," she said.

Alastair sighed. "You're already strapped in. I'll change you when we get there."
With that he walked outside and began taking Lexie towards the fair.

Lexie squirmed. "I can't go there! Every one will laugh at me!" She yelped. She REALLY should have gone that morning before breakfast but now she had changed her diaper and she'd have to sit in it...

Alastair paid little attention to the girl's complaining. He reached down and put a pacifier in her mouth and tied to the other end of it to her onsie, to stop her talking.

Lexie just let it fall from her mouth. "Come on, PLEASE? I can't crap my pants in front of the whole fair! I really gotta go!" She pleaded. "Just turn around. I promise it won't take long!" She begged, her bowels straining against her to go.

"I asked you earlier if you needed to go. Now you have to face the consequences of lying." Alastair said in a stern tone.
"It doesn't matter anyway." He said. "Nobody cares if a baby goes in public."

Lexie squirmed again. "For fucks sake, just let me go to the bathroom this on... oh no..." That last part was because she couldn't hold it any longer. She remembered the sensation of the mess pouring out, warming her behind and making the diaper sag a bit. "Asshole!" She yelled at Alistair. "This is your fault!"

"Someone's still cranky." Alastair said in a mocking tone.
"You're lucky that we're getting changed at all." He scolded. They were already approaching the fair, so she wouldn't have to wait long.

"Come on, you jerk! At least change me before we get there!" Lexie begged him. She tried to undo the clasp but couldn't, so she tried to tear the straps but couldn't. "You (Redacted for length of profanity)!" She screamed at him.

Alastairs eyes flashed with anger. "At this rate you be getting a spanking aswell as a diaper change." He said as they arrived.
Alastair began looking for a baby change room.

(Do you want him to find one or do you want it done in public?)