[Because he will bite. Hard. Sure, he barks a lot. Loudly. But such a short fuse means he's not far from a chomp. Or in Bakugo's case, a boom. Still, there's a closeted nerd in there about other people's abilities. Asking about Ragna's ticks a small ping of interest and excitement. Does he need to know all the details? Fuck no! Don't bore him. But having a general idea makes for a better clash when they do go against each other. Damn right he plans on training with him!]

As in lifespan or vitality?

[The idea of someone dragging "lifespan" out is kinda bullshit, but it's happened in comics, so he's not "WTF" about its potential. Sucking out stamina or energy and calling it "life" happens way more. Clear it up, Ragna!]

Yeah, it's similar to nitroglycerine. [He's not going to immediately let the guy know he can only do it from his hands, doesn't trust him completely yet, but if Ragna wants to assume, go for it.] Uh-huh. 80% of the people in my world have a Quirk.