She should sound like the hot-headed brawler type of character. One for picking punching something as a solution to most options, she's the more violent type of Demon Lord but with a heart of gold despite being a hellhound. A tried and true tsundere who has yet to realise her preference in women over men until the time of the main story, she'll try and be in denial when it comes to facing her true feelings despite her reactions making things very obvious.

Current reigning Demon Lord of Vulcan, she leads her kingdom confidently and competently. She believes in strength above all else, but acknowledges that strength comes in many different forms, essentially the one area where she uses her brain is figuring out other people's strengths and trying to coach them for betterment. 

She's in her mid 20's and at the top of her game. Hephaestus should have a voice similar to Beidou but a bit of a more aggressive/confident tone, and given your own unique spin of course. Whatever you think could fit a lean mean punching machine type of brawler.

Hephaestus is also very adamant about not having people look her in the eyes due to a hereditary trait she has, which is why she grew her fringe out to cover her eyes.

As stated prior with Alice, all voice clips for this VN won't be full dialogue, instead there'll be short phrases or sound effects/reactions that cover the general feel of the scene. Current word count is up in the air but doubtful it'll hit triple digits.