So had a bit of a thought inspired by The Lion King/The Lion Guard.
What if Heather's implied abilities as a seer included not just dreams and insight, but visitations from and/or the ability to communicate with the spirit of King Jupiter?
As you might guess, the main inspiration for this is Mufasa's appearing to Simba and others after his death in the original The Lion King film. I'd imagine such scenes would make for some pretty epic, solemn moments. Though it might be a bit frustrating for Jupiter not to be able to warn Heather about Bleston.
Alternatively, if you took a more humorous take on this concept, it could lead to some funny and/or awkward moments. I can totally see Jupiter being like "Heather, dear, I don't mean to pry, but I'm pretty sure I know what the S in that heart you drew in your journal stands for."
It also reminds me of Redwall, but Martin's spirit appears only on moments of danger and in dreams. But I liked the awkward moment part. It would be intersting to add it to a possible Green Ember Series or Movie for a comedic tone.