I've been playing fire emblem echoes shadows of valentia which is a remake of fire emblem 2. In that game Alm and Celica are fated lovers both with marks on their hands I feel their ring and bracelet would be a set together with this idea

That is cool ^^

What about the intro song Emblem Engage what would be there Invocations
Rise from a thousand years ago
Shaking off a hazy Dream (Tiki)
Meat the Flower (Alfred) who Cares for everyone (Celica)
The Rising Force (Roy) of Blacken Steel (Diamant)
Fighting (Ike) in the Desert Sands (Timerra)
Meet the Snow (Ivy) that Sweeps Across (Lyn) the field
The Light (Alear) and Dark (Veyle), Restore (Eirika/Ephraim) our Skies (Camilla) tonight
Heal (Miciah) the wounds and Learn (Byleth) from Yesterday
You calling out their names
Crossing (Rivals) paths again
Twelve are coming through
Bless us from another place do you Remember me
Memories of Red and Blue
Reigniting you (Lucina)
Bare your fangs (Corrin)and all
Free yourself (Leif) forever more here and now
Emblem Engage
Bonds of Fire, Connect us (Alear)
Love Provide (Sigurd), Protect (Hector) us
Like the Heroes of the pages (Veronica)
Like the Stories of the ages.
Bonds (Chrom/Robin) of hope Unite us
Shining on (Marth) to Guide us (Soren)
Skies (Camilla) above Embrace the beauty
The time is now for you and me

Hmm I don't know all the character's here some of it might be because I'm bad with names but who I do know mostly seems pretty dead on, your dead on with Celica, Roy, Marth, Soren, Hector, and Ike

I get Lyn is because they changed her to an archer instead of a sword women in this version for some reason.
I think though Lyn would fit better with "Bless us from another place" as her all Arch is the fact that she is the last surviving member of an indigenous tribe and learning that her royal heritage from she try to rebuild her fathers kingdom and honour her mother and tribe indigenous heritage.

Her tribe was only killed because the her uncle didn't want someone alive with a legitimate claim to the through since she has royal heritage

Thanks for the insight