The thing is we’ve seen it change Dahlia when she died we saw that this wasn’t normally her. In the past she was kinder and more loving of her sister. Also the main reason Bonnie was consumed with expression is because she was only adept at magic and she overwhelmed herself and overused the power. Like when you’re a new zoo keeper is dealing with a tiger for the first time by themselves . Yeah they’d have an understanding because training with that animal but they’re extremely inexperienced. She never dipped her toe into expression and learned a lot about, she just jumped in

Alaric told Hope that black magic was poisoning her mind, it could be a side effect of using it. Somewhere I read that Hope is less susceptible to black magic because she has vampire blood in her body (black magic) and the Saltzman twins may have physical side effects (e.g. vomiting) because, as we know, the gemini bloodline has some unidentified darkness in itself.

Yes, dark magic somehow changes their ego, in the case of Dahlia it wasn't black magic, she was already tough even before Mikael's kidnapping and the Vikings, what made her so was the revolt of having been abandoned by Sther because of a viking who tortured her she just wanted to be in peace she didn't even chase Mikael, she only used revenge against Sther after Klaus refused to fulfill Sther's deal.

@Sean 175 I don’t think Esther invented Dark Magic. I’m sure that when Hope made that statement, she meant Esther practically invented Vampires, who are practically dark magic beings. If Esther actually invented Dark Magic she would have hardly turned to other forms of magic for power and totally dived into darkness. She also stated to Dahlia that she would return to the Dark Arts, meaning it wasn’t something she invented, especially given that Dahlia practiced Dark Magic before Esther became serious with magic in the first place.

I think it has more to do with the Witch personality and beliefs that dictate how their bodies is going to express Dark magic. As Hope(and later Josie herself) pointed out that part of the reason Josie went bad is because of herself. A part of her wanted or believed she was going to be bad while practicing Dark magic. Thus she became bad. While other witches who have practiced dark magic hardly ever went bad. Cleo said it best to Kaleb, it’s about a witches intentions. Now whether this magic can be used to hurt the Gods…I’m not so sure. Maybe if they get creative in how they use it to attack.

@WyattHalliwell419 I admit it’s possible that may have been what she meant. But I still believe she meant her gram’s invented Dark magic. Esther was a genius, so it fits that she would be the one to invent a new and powerful form of magic to help her one day fight her sister(well at least it does to me).

KnocknickKnock - You didn't get my point, so sad. That was an example, Knock-Knock-Knock by Twice. You can see Bonnie being affected by Dark Magic after stop Jeremy's heart in season 2, The Vampire Diaries.

Neither Papa nor Inadu didn't use Dark Magic, it was sacrifical magic in Inadu's name via her bones. Eva's case was also sacrifical magic (she killed the kids and the regent of the nine covens to grow her own power). Vincent was the same since he was on Eva's thingy "the more power better". Davina's case is probably because she had a coven so they shared the cost of magic, which it was probably why (the witches in New Orleans that used the ancestral magic probably had this advantage because Sophie brought Celeste back to life and she'd seem to have no problem).

And saying Inadu wasn't affected by that magic is pretty, sorry, insane. She'd literally go crazy and killed everyone in her village and cursed them later (even her mother).

Again, there had been a misuderstanding here. I didn't mean "affected" like "OMG! They have black eyes and dark painted hair, oh no!", but it could be read in thousands of ways.

Sacrifical magic needs sacrificies, dark magic doesn't. Dahlia was the first one in scene to use that type of magic (dark magic).

Anyway, thank you for your time :)

Dom Gand - Dahlia's personality did not change due to dark magic. She never was seen doing dark magic after she created her own magic signature. She changed her personality probably because of what she and Esther has passed through in Vikings' control (and Esther abandoning her could be "reasonable"/the problem).

Bonnie lost control because expression was too much for her and that's not my topic.

JesseSs12 - I also thought about their bloodline that invented dark magic.... Who knows?

WyattHalliwell419 - Esther was already serious in magic, but when the white knight swore to protect her, she perhaps gave up of magic so that's when Ayanna starts teaching Esther magic like her mentor since Esther never was serious about doing magic because Dahlia was the head master in the game (writers stated that, not using these words of course).

I agre with NovakOwinchester