Well, we have seen Deus interact with the shopkeep and he bullied him, he's technically a lv 4 but a mad strong one. Though IIRC Henri should've already interacted with him
Can Liz and Amber eat strength? Tanos says that the Strength Eaters' power is to teleport through water, and that their energy absorption is "something quite different". That kind of makes it sound like it's not an innate ability of theirs, and that Liz and Amber wouldn't inherit it.
Henri has interacted with him, yeah. We see Henri in Shopkeep's shop at one point, asking him "hey, you look weird, are you a really corrupted superhuman, too?". Which is just rude, Henri.
Like i said "deus could be allowing shopkeep", I guess shopkeep didnt offer him the rune becuase Herni was rude
but "logically" it still kind of hurts the idea that shopkeep knows everything (in the same way deus does at least)