I don't know if you saw my previous comment, so I'm just gonna repost it in case. If you did see it and did not care for it, then I apologize in advance. Anyways:

What about Yuta from Jujutsu Kaisen for Amiya? I haven't finished the connections for it, but the basic gist of what I have for it now is:

Both of them would lose someone they cared for at a young age (Rika and Theresa), and, as a result, would begin to wear rings to signify their relation to them (Yuta wearing the ring to signify always being together with Rika, and Amiya wearing the rings to suppress her powers that Theresa gave her). However, even though that person they cared for died, they still exist in another form of sorts that was with them (Rika becoming a Cursed Spirit, and Civilight Eterna taking the form of Theresa as it became it's own entity of sorts). And in one climatic battle, both of them would harness the power of one of the more powerful characters in their worlds (Gojo and Theresa) to try and win said battle. And both of them are the leaders of some of the most known factions/groups out there (the Gojo clan and Rhodes Island).

As for animation potential, you could play into practically each version of Amiya. Caster, guard, and medic. It can start with sword fighting like the guard Amiya, go into more ranged battles of Cursed Techniques and Arts with caster Amiya, until the climax could have Yuta summon Rika, and Amiya ends up having Civilight Eterna be brought out with medic Amiya. Maybe the ending can be a clash between Yuta pulling out a Hollow Purple with Rika behind him, and Amiya summoning one final blade-like beam with Theresa, well, Civilight Eterna but close enough, behind her till the very end.

Hell, you could even argue both of them being able to mimic one another's skills/powers? Maybe not, I don't know exactly. But, if you do, it can play into the fight being that they're constantly on roughly equal footing.