Hey! Here I am having taken forever to reply to this because, April.
So of my three: Jesse obviously hired him, he seems responsible, Jesse likes him. Ruby is just an intern and probably doesn't know him, she's focused on the animals. But Gloria works in the apothecary so she's making all the potions he works with, would see him fairly often AND she went to Unseen University at (some of) the same time: 2010-13. And they may have had some classes in common there because she was studying potions and alchemy.