There was an incident that had happened prior. Lucario got caught in it rather badly. Fortunately Corviknight was able to fly him over as it were, bringing him to the care of a male and female Indeedee.

Corviknight surprised them both pretty hard when he arrived. Both Indeedee were shocked and greeted to a large bird several times their size, with someone in their closed talons no less. Corviknight then passed Lucario through air-transport. Corviknight, despite how large, is obviously experienced in controlling himself and setting Lucario onto some kind of roller board of Indeedee's, it was way too flashy for Lucario. He should know, he wasn't actually unconscious or anything, just could hardly move.

So here we are. Both Indeedee seeing Lucario off after recovery. Big ol' Corviknight waiting standing halfway through the entrance looming over the two. Lucario waving them off has he walked to the exit. Before the Indeedee knew it, those two were right back to flying off again.

This time Lucario was riding on Corviknight's back, of course, no doubt there. In fact Lucario would've made sure to ride on Corviknight's back to get to recovery in the first place, but was way too exhausted.
It was one thing to use Corviknight's talons to hold onto by hand so Lucario could scout the area below, but to hold Lucario's body whole like that, he didn't appreciate too much and figured Corviknight would get a chuckle out of it. After all they've been through, Corviknight knows what Lucario is about. Lucario knows Corviknight means no harm.