With the assurance of an Oath, especially from a person as strong as Bo, Ackster felt slightly more at ease as he agreed to share his secrets. Of course, he was still reluctant about divulging the fact that he was from another world, in which Millmiria and all its inhabitants were fiction.
Bo would most likely think he was crazy. But it would be too late for him to go back on his word.
Other than that, Ackster wasn't overly worried.
Keeping his secrets secret would keep him safe. Even with the Oath in place, Ackster still couldn't completely let go of his paranoia.
However, his secrets wouldn't help him grow stronger. Bo would.
It was the logically most sound decision to agree to the Oath. So, that's what Ackster did.
