oh man, yarrow sounds like he's been through quite a lot! I don't think the stuff you have now is too dramatic - we've got plenty of folks with heavy backstories, and i think that might even be a bonding point/jumping off point for new CR!

provided he wants to open up about it, which he might not,

AS FOR PRE-ESTABLISHED CR....Ekkehardt is part of the medical staff and definitely would at least be hovering for a bit to make sure he's recovering from what he was put through in captivity so Yarrow could easily know him through that, if you're ok with it!