[SPOILERS] Need some spoiler free assistance on navigating an alternate ending

Be warned there will be some mid to near end game spoilers below.

I have currently given the blind maiden the fingerprint grape and I figured this has something to do with the frenzied flame ending. I assume that she will be in the area behind The Cathedral of the Forsaken next but I have not explored much there yet.

I am also fighting the fire giant, and thus I know I'm close to the other endings conditions.

My issue here is that I'm wondering if I'm locking in a specific ending by doing either before the other. For example, if I make Melina the kindling as she wishes, does that mean I'm shut out of getting the frenzied flame and have to do the initial ending?

I am hoping for answers that provide as little spoilers as possible. I still have the main massive section of the upper world blocked off so I know there is another area to explore but I figure that may require me to continue playing. I would like to find this all out organically without feeling like I closed off other endings.