A small massacre
For the first time in many years, Kayden found himself alone again. Your attitude or mindset has not changed; he just continued cultivating and studying the blue liquid. Loneliness didn't weigh on Kayden's mind. He could spend millennia in this place just doing the same things every minute of his life, as long as the slightest progress was made. He would have no discouragement in continuing.
Loneliness didn't change Kayden's steps and, quickly, a few years passed. Much more than a few years ago: only five centuries later, Kayden achieved true mastery with the blue liquid. He had nothing more to learn from this liquid. During this period, he did something ridiculous: changing the base of his body to blue blood. It wasn't a very high amount of liquid, but it was still an emergency reserve.