Nessa

fisher, your average elusive lake monster without the monster part

Both Xile's and Ness' lineages have gone far away from the original shade-imprisoning gaolers, however both have circled back to Ice so they are more aware of the gaoler traditions than, say, Emrys or Zaril, who don't even care to learn (along with Rimma, who knows and doesn't care, and has adapted to the modern Sornieth extremely well and always wants to see more of it instead of being a prison warden). Romana doesn't really count in that, hers is a more complicated situation.
At some point out of curiosity considered what order would either choose if they were obliged to. Xile felt more inclined toward becoming a sentry (outside but not too proactive) while Ness would be a keeper (not too scary, but more serious and she handles dark enclosed spaces a lot better than daylight).

Song quote: "I Lived" (OneRepublic) 4/12