Sloth thought William was acting weird thanks to the long coma he suffered recently. In fact, he acted out of kindness before, but William mistook his actions.
"This isn't related to that comma," William muttered to himself, while feeling harder the closer they got from the ground, "it's not a spirit power suffocation… It's like a clash of something from outside with something within me… Is it related to that spirit?"
William couldn't help but move his attention towards the spirit he gained lately from here. That monster was bizarre in the first place, and its spirit must have held tons of secrets, rather than the ones he explored already.
But as Sloth was walking normally, he had to keep up. He had no time to investigate what was going on, and so he decided to activate his spirit at once to counter that pressure.
"Using that this early on?!!" Sloth paused when William's fox spirit appeared, "do you want to retreat and let me handle this?"