...yyyyeah I think his dead brother would make for one hell of an echo, sob. But yes, given all this I think Robin's right up there with people that are awesome to hang out with for delicious magical purposes, even if the creep factor is high with this one. (But hey, she hangs out with Sam Winchester and his hell echoes, so...)

She probably doesn't have the knowledge to really perceive much about his true nature apart from not-human and glamour-battery, but he does fall outside of the Realms she has, so she can't directly affect him with her arts, lmao. That will send up a warning flag.