I wonder if you'll give them passive skills that contribute to the player even if they themselves don't have them, like you did with Billy's Plant Knowledge II, which let's you pick grade 2 wild plants, or Suong's Butchering, which gives you the meat of the animals and abominations you kill. You know, stuff like chopping more wood with Marcus in your party, or finding bullets/minerals on dungeon chests being more likely with Olaf/Valdemar respectively in your party.
I genuinely expected Tadeas to have Plant Knowledge III as a passive skill on my first run, haha.