Dyon had long since devoured Valen's memories. With his added control of [Devour] after reaching the One with Self Realm, he could even pick and choose which memories he snatched, allowing the latter to keep his life. Of course, this was only a recent ability he gained after he had refined his soul qi control through decades of pill concocting.
Valen's life may still be useful to him… So he kept him alive for now.
Unfortunately, Valen's memories didn't have anything useful in them. Apparently, his only mission was to enter this place and find his Ancestors. Other than that, he was meant to inform them of the situation outside. Beyond that, there was nothing.
Dyon didn't believe that things could be so simple. But what he did believe was that Valen didn't have the right to know the truth.
A drop of blood appeared in Dyon's hand. Of course, it wasn't his own, but rather, Valen's.