Ruto is know as Kurobara in the underground. He's a villain with the quirk of Hypnotic voice, allowing him to influence the emotions and thoughts of people he wants. People can resist against it but it can be difficult. If he decides to use his quirk on someone he has to touch them and say "emotional."

If he uses the quirk on you, you can tell he's using it on you, it's just you can't control your actions, at least not very well. Most of the time though he's able to get what he wants through manipulation and charisma.