Luigi and Yoshi were hidden inside the branches and leaves of one of the trees among Peach Garden. It was a perfect spot for confidential talks; while the one inside could hear sounds from the outside, people outside could hardly ever hear what would be going on from the inside—that is, unless they would think of going near, in which they wouldn't even dream of doing. After all, why waste time listening closely to the sounds within a tree?
"Okay, Yoshi, tell me again why we're here, hidden in the treetop?" Luigi asked Yoshi critically.
"Because treetops are perfect for pep talks," Yoshi explained....

Luigi and Yoshi walked their way past the Castle door. Yoshi glanced once at the green plumber as the duo made their way deeper and deeper into Bowser's territory, and was replied by Luigi's nod—and a straight set on his pursed lips.
Soon Luigi stopped; Yoshi felt like he should do the same, too.
"Luigi?" Yoshi asked, staring intently at the thin Mario brother's face, looking for some sign of regret—like he'd wished he'd let Yoshi talk him out of the whole rescue thing in the first place.
But, to his surprise, there was none.
"What's wrong?" Yoshi asked again; the silence was getting to him....