Fia is still quite wheezy here with “giving warmth” and “holding” warriors before battle. However, we all know what this means in the real world. I like to think that there is someone else who can comfort the warriors, even if it is more about gathering strength for their lord to revive.
If you’re going to do the Ranni quest, you might as well warm up to Fia. Especially since Ranni came across as quite cold and distant in the first playthrough. Fia makes a much closer impression.