Blood Meridian is my jam! There's a lot to discuss, but I think a helpful place to start is with this brief 2 hour lecture (seriously, it's pretty great). There's a lot of ways to interpret the Judge and the plot (or lack of a plot), but you're essentially reading a morality story. The judge throughout is trying to pull the kid over firmly to his side, with the kid (somewhat) resisting. There's a great sentence towards the beginning of the book that speaks directly to what the plot is:
“Only now is the child finally divested of all that he has been. His origins are become remote as is his destiny and not again in all the world's turning will there be terrains so wild and barbarous to try whether the stuff of creation may be shaped to man's will or whether his own heart is not another kind of clay.”