High Situational Awareness for Snow: Canonically Fiona is able to survive, solve complex puzzles, teach herself basic alchemy, train and care for a dog, and scour a large manor for anything remotely useful, all while being stalked by deranged madmen. She’s a smart cookie, and Snow could afford to be a bit more aware of her surroundings.
High Situational Awareness for Zena: let’s be honest she’s fairly likely to use this as a method to quickly identify random metal objects she can snort for magic powers. I’m not saying that’s a bad us of her time, to be clear.
Familiar for Gil: Fiona’s companion, Hewie, is an unusually well behaved stray German Shepherd she met on the worst day of her life. He’s very brave and unusually intelligent, but not to the point of exceeding “unusually clever medium sized dog.” He’s considered an aspect of Fiona’s character, so we can get him but he won’t be considered a full retinue member and we can’t (for example) use cards on him.
Rapid Recovery for Gil: Fiona is not actually very strong, fast, or tough, but she has a substantial inner wellspring of will and stamina that allows her to recover relatively quickly, as is common in survival horror protagonists. She can sprint until she’s out of breath, take a few moments to compose herself, and then do so again in a consistent cycle for most of a night (while also occasionally getting into brief, escape focused scuffles with deranged madmen). This will allow Gil to recover rapidly and manage without sleep much more effectively than he already can.
Rapid Recovery for Ireena: In addition to helping her shrug off radiation better, this will allow Ireena to become a towering and unstoppable Minotaur MMA fighter that needs just a minute or so to be back up to full fighting trim (other than actual injuries)
Rapid Recovery for Rose: I noticed that Rose had a weakness in that last arc. Can’t have that. She’s working all hours already.
Azoth for Candress: More of a liability than an asset for Fiona, but she has a deep and powerful pool of mystical energy known as Azoth within her. She appears to be the only character in her game that doesn’t have some big plans for how to use it to perform miracles of one kind or another. Candress could probably use it as a mana battery, allowing her to use her magic to some extent even in lower power or magic dead settings. In a setting where she can actually use magic normally, it’ll instead manifest as a drastic uptick in mana regeneration.
Azoth for Keilnei: Similar logic, but allowing Keilnei to use the Gift of the Naaru and her Ranger nature magic instead of Warcraft arcane magic. Both can use materia.
Azoth for Snow: Snow can already cry pretty close to at will, but this will lace her tears with Azoth. Azoth can do a lot of miraculous things. Snow won’t necessarily be able to (for example) fix brain damage or cure mist madness with her tears, but I’ll actually roll to see if she pulls it off instead of just saying no. She’d also be a lot better with cure materia!
Azoth for Gil: Unfortunately, Azoth is found in the uterus for some ungodly reason, so Gil would need to make a few physical changes too if he wanted it.
Full swap for Boulder; we don’t need two big violent dogs. This will leave us with a busty blonde with all of the traits below and a clingy personality that loves physical affection. Comes with “free” additional dog in the form of Hewie, who is much smaller than Boulder but a lot better behaved, and a gacha for “selling” Boulder’s old doggy body.
Full swap for Mei: Frankly Mei is useless as things currently stand. Fiona isn’t a good fighter, but she’s been known to struggle to moderate effect and is a lot better at taking care of herself. She’d also be able to feed Terra a lot more magic in the form of Azoth, allowing for her to use Terra’s more mystical powers to greater effect.
Full swap someone later. We will definitely run into someone useless eventually, or need a one up.
Sell it at the bazaar. If there isn’t anyone there that wants to have the ability to turn themselves or someone in their retinue into a hot, situationally aware blonde living macguffin who is great at intermittent sprints, I don’t know what the multiverse is coming to. She even comes with a free guard dog!