In the old days, a cartoon Canadian Mountie named Dudley Do-Right fought week in and week out against the dastardly villain Snidely Whiplash. At times, Tenorio can be a real Snidely Whiplash, even down to the villainous facial hair (though Snidely sported a mustache and Tenorio has a beard). Like a cartoon villain, Tenorio dedicates much of his life to revenge and nothing else.
In fact, almost every scene in which he appears features him shouting about how he's going to take vengeance on Ultima or Narciso or Antonio, who, by the way, is a tiny, innocent child: "I will find a way to get to her and destroy her!" (16.76-77). See what we mean? You can almost hear a loud cackle accompanying a line like this. This, along with many of Tenorio's other gems, demonstrates an obvious commitment to revenge, but it also shows how he views this as a battle on a grand scale. He's not just going to kill Ultima; he's going to "destroy" her. He means business, and this is the Big Time.
Now, just because Tenorio skews a little cartoony from time to time doesn't mean he's not a seriously bad man who should be genuinely feared. He kills Narciso in cold blood, and he tries to kill Antonio—a kid!—on more than one occasion. Tenorio wears the label "villain" well, and most people are too afraid to stand up to him. The fact that Narciso and Antonio's father not only stand up to Tenorio but out-muscle and outwit him goes a long way in shaping Antonio's idea of how a man acts in times of crisis.
When looking at Tenorio, though, there is something to keep in mind. This story is told by Antonio. As he narrates, he's looking back on his younger self, and the story is heavily filtered through his memories of childhood. That's not to say that Antonio's ideas about Tenorio are false or that Tenorio is not villainous. But there's one aspect of Tenorio's life that Antonio (and Anaya) fail to spotlight.
He is a mean drunk and a coward from the get-go, but grief may play a part in him crossing the line into true villainy. Tenorio's accusations against Ultima come after his first daughter dies. The murder of Narciso comes after Tenorio's second daughter has fallen ill, and the killing of Ultima's owl, which of course ends up killing Ultima, comes after Tenorio's second daughter has died. None of this justifies Tenorio's actions, but it is a facet of the man's character and life that remains all but unexplored in the novel. So it's not a bad idea to think about those things when weighing in on Tenorio, because it may just be that we don't have the whole story.
Beyond serving as the straight-up antagonist of the novel, Tenorio also plays a—dare we say?—much more important role in the novel. Of course his actions mark huge moments in the book, but like most things in Bless Me, Ultima, what he's really doing is allowing Antonio the chance to further ponder the Big Questions about the world.
The fact that Tenorio could kill Narciso and go unpunished by the law or by God, raises major doubts in Antonio's mind about how God operates or if He even operates at all. Antonio just can't quite bring himself to have faith a God that would let an honorable man like Narciso die while allowing a cowardly murderer like Tenorio roam free and murder some more.
In the end, Tenorio gets his just desserts, but by then, he's already killed the owl and ensured Ultima's death. With his death and hers, the struggle between Good and Evil that exists in the book dies, too, and one must decide if Tenorio deserves forgiveness for the role he has played. As crazy as it might sound, Ultima believes he does, arguing that "'With the passing away of Tenorio and myself the meddling will be done with, harmony will be reconstituted. That is good. Bear him no ill will'" (22.138-141).
Forgiveness has played a large role in the novel for Antonio, so it's no mistake that Anaya makes these some of Ultima's last words. Antonio has struggled to find a god who forgives or to even decide who deserves to be forgiven and who doesn't. With this—a sort final piece of wisdom—Ultima shows Antonio that even someone as cruel and misguided as the villain Tenorio deserves to rest in peace and to have his sins forgiven.