If you told anyone you had a "goth best friend", a picture of someone who wears all black, maybe even wear eyeliner and all the MCR merchandise might come into mind (even though that's not true).
But Herselie Archeron, despite living in a dark cathedral haunted with (kind) ghosts, her family being dark melancholic and morbid people (though they're pretty friendly), being a die hard goth-music fan, and her dream of becoming a hearse driver...she wears pastel and colorful outfits, and she has an otherwise bubbly and extroverted personality. She is technically goth but, well, it's hard to picture herself as one by how she presents herself. You'd think she's all about anime and cuteness by the way she looks.
Heck, even her room is all pastel pink and rainbows with such cute decorations everywhere! As Herselie rants to you about how her failed driver's test, you can't help but look around her bedroom...it really contrasts the whole cathedral and her other siblings' room - that were very dark and gothic. It's like her room is the only colorful thing in this cathedral home of theirs.