Dealing with Bloodthirsty and Cruel

[Zetshia]

I've seen a lot of people claim that the only way to get rid of the bloodthirsty debuff is to fist fight but that's not always true. If the sim is a monarch, knight or spy you can satisfy their blood lust by sparring, which is a friendly interaction that gives pretty good xp.

As for the cruel trait, you can work out your pent up anger on the quest specific sims who don't stick around after the quest, or by yelling at children since kids can't attack you and don't help with quests. It's mean but it works.

[Signal]

What I usually like to do is right after I do something to satisfy a hero's Bloodthirst or Cruelty negative moodlets, I turn around and immediately have that hero apologize to the person they just got into a fistfight with or did something mean to. This repairs most (if not all) of the social damage. You can find the "apologize" option under the "friendly" interactions options immediately after your hero did something mean to another sim.

[Schipperke]

I haven't tried the Cruel trait, but my first Monarch was Bloodthirsty, and fistfights always removed the negative moodlet - if he won.  If he lost, he wasn't a happy Monarch.  That's why I always had him pick on the maidservants, he could usually win a fistfight with them.