OOH, better get my post in before bed! ;D
(leaving OC ref due to not being related to the dragons)
OR
Name: NIGHTMARE (first) Overlord Zero (2nd; Can also be referred to as Zero)
Relationships: Tbh, the two are married, lol, but I may seek lore for one or the other unless you want to do them together.
Theme of story: (in general) Horror, maybe some morbid humor (still SFW/FR). Neither would have real world based stuff such as domestic felines or canines; They'd be more fantasy/sci-fi based with creatures like anthro spiders or something.
For NIGHTMARE alone, horror for sure; I'd super love to see him toying with others' nightmares and fears. If you're up to claw scraping shenanigans, then that's perfect! He'd be higher priority due to being spooky season. xD
Zero alone, probably a little dark, but more alongside her possibly getting revenge or simply being worshipped by others. My main ideas for her are more alongside either her and NIGHTMARE causing chaos in other (fantasy based) worlds or hanging out together. Otherwise she's one of my self indulgences so honestly...Worshipping her? Perfect. Cowering and groveling before her boots? Heck yes. xD
Personality Traits: Both are rather sadistic, cruel, and have a great empowerment by being hated and/or feared. They also love each other very much, but struggle with expressing such. They are an ace couple.
NIGHTMARE: Plays with fear, torments others for fun, and is driven by absorbing negative energy.
Zero: Self proclaimed villain, enjoys that life, and driven by lust for revenge against mortals who turned against her and/or expressed hatred toward them.
Physical Traits: Refs above show pretty much everything; Here are links to their Art Fight profiles and dragons:
NIGHTMARE:
Art Fight +
Dragon
Zero:
Art Fight + Avatar is dragon (in sig).
Length of lore: While I personally write full fledged stories and love seeing longer takes, it's all up to you. :3
Background Info: On profiles~ Feel free to ask about things though, since they're both rather new still and an everlasting WIP. :3