Actually a tough question. For all her interest in Leviathan... I mean, she fights with a Leviathan-egi and has a special grimoire crafted with a souvenir from that fight... she definitely isn't interested in serving him. He and his have done too much harm to her friends for her to even consider it.
The others are either way too destructive (Ifrit, Garuda) or too passive (Ramuh). I think she'd be most sympathetic to Titan's cause.
Val would likely get himself tempered by Ramuh...dumb guy getting way too close given his interest in the primal.Â
Ziv I would've said Levi before but after nearly drowning and watching a number of people he did care about die because of that accident, he's been pretty much terrified of water so that would be difficult. Ifrit if anyone. He grew up around and has always been fascinated by the Amalj'aa. I need to know more about Alexander, but it kinda suits him.
Alaire MIGHT be willing to work in a sense for Shiva. MIGHT.Â
Bastian....kid doesn't want anything to do with Primals.
Shiva, by and far. That's right Boys, if serving a Primal. Roh would become a heretic!
Roh respects those who unflinchingly fight for their beliefs. A woman who is so fully dedicated to her cause she herself becomes a Primal, how could he not be inspired by someone so dedicated to forging a peace in a year long war?
I'd like to say Ravana, being the belligerent Flynt is, wagering favors (and likely gil) through rite of combat. Army of ant soldiers would be radical too, just chillin' and eating Nanka until you gotta go an start a military campaign... Man, I wanna be a Gnath. All glory to the Hive.