They didn't need to.
For the first time, the promise belonged to more than one father.
After Mark's visit, the project changed in ways nobody had expected.
Until then, Doc had been relying on information supplied through Rachel, Ellie's therapist, and the medical team. Those conversations were necessary, but they couldn't fully describe the thousands of small adjustments that made Ellie's daily life more comfortable.
Mark understood those details because he lived with them.
He knew which positions caused Ellie to become tired, how carefully her head needed to be supported, and how quickly an enjoyable activity could become exhausting. He knew that she disliked feeling strapped into unfamiliar equipment and that she became frightened when adults moved her without explaining what they were doing.
He also knew something the engineers hadn't thought to ask.
Ellie hated being unable to see what was happening around her.
When she sat too low or too far behind something, she felt excluded.
She wanted to see faces.
She wanted to look toward the front.
And she wanted to feel as though she were participating rather than merely being transported.
Doc listened carefully as Mark explained.
"She doesn't want to feel like luggage," Mark said.
Doc looked up.
"I wouldn't either."
Mark glanced toward the proposed seating position.
"Then make sure she doesn't."
Virginia, who had joined them for the discussion, wrote the concern in her notebook.
She didn't promise that every preference could be accommodated.
Instead, she explained which questions would need to be reviewed with Ellie's therapist and which features could be considered without compromising the design.
The conversation lasted nearly three hours.
By the end, Doc had discarded another set of sketches.
He didn't complain.
For the first time, he was beginning to understand that the most important part of the vehicle wasn't its engine.
It was the experience of the child who might eventually sit in it.
A week later, Doc visited the Forrester home.
He arrived carrying no tools, no camera, and no dramatic announcement. Rachel had invited him to meet Ellie in her own environment so he could understand more about what she enjoyed and what made her uncomfortable.
Ellie was waiting beside the living room window.
When she saw his truck, she shouted, "The Harley man is here!"
Mark laughed from the kitchen.