They're like Robin Hood. Oh, thank you, older self, thank you thank you for making this an adventure, and not a desperate gamble to get home before disaster strikes.

"I can do sad eyes!" he agrees, watching as Vash hauls his stuff out of the broken down caravan they've been leaning against. And then, just testing out the name... "...Robin."

What? He can't call Vash Vash, and relying on mental speech only works if they both can talk that way! This is safer.