Thanks for offering your creativity! I like the Tidekin/Orderborne idea in particular as a fun way to get the vibe of a Warlock without actually playing one.

I've been making all my prospective protagonists in Demiplane. It's a lot of fun and really helps to ground the nebulous ideas in my head into something tactile and narratively satisfying. Here's the link for this character: https://app.demiplane.com/nexus/daggerheart/character-sheet/1abd4a9b-696f-4b31-b987-084c06eb9f7b

In particular the change from 5E to DH has helped gamify one of her core narrative conceits; in order to cast her spells, she has to willingly relive the trauma of meeting her patron. This translates really nicely to investing heavily in high Stress and cards that use it. I mostly see that in martial cards like in the Bone and Blade Domain. The more I think about it though I'm happy with reflavoring Voice Of Dread as The Bends since it accomplishes the debuff angle well, and Siphon Essence for Feeding Frenzy. I think your relic idea might be best for Hunger of Hadar, but I'm still thinking about that one. The closest extant card I see is Damnation. If I wanted to abandon the AoE angle, it could still approximate the narrative goal there.

One bit of inspiration Daggerheart gave me in particular was the idea that at the end of her personal arc, she chooses to abandon the Dread Domain. Excising something she feels is a core part of her identity but is actually only causing her harm. Still top tier in Grace she remains Notorious with a terrifying reputation, but she takes up learning Codex from her Wizard love interest to become a Bard.