As long as you touch them at least once, even if just a handshake, they will build addiction and eventually visit you to ask to touch you to lower it if you don't touch them for too long. You can take advantage of it, of course, they will get angry but eventually will need too much your touch to complain for long.
For now all those do is increase your level and money. There was a main story promised ever since it was just rogue, or was it just rogue and kitty, but pretty sure it is not happening.