Wessels has been trained in both jazz singing and classical singing. She was first trained in jazz, but later her instructor suggested classical singing to her. However, Wessels has stated that she found classical training to be very restrictive, and so she likes to do something "in between the classical and the jazz stuff, and if you look at classical music with high vocal lines, then you kind of get to gothic very soon!"
Wessels became involved with Delain in 2004 when she met Martijn Westerholt formerly of Within Temptation. Since the band was meant to be a studio project only, Westerholt asked if she could write some lyrics and vocalize which she thought it was going to be a one time thing. In 2005 they signed a deal with Roadrunner Records. She is the lead vocalist and primary lyricist of the band.
My parents had quite good taste in music so I had some of the classic rock influences; Pink Floyd, Deep Purple, Genesis, Led Zeppelin, and Kate Bush. My brother really got me into metal, those were really the high days of Metallica. Actually, Toxicity (2001) by System of The Down is still one of my favorite records ever. Right now, I am really into the alternative rock scene, Radiohead is my favorite band ever. I adore Muse and Nick Cave. Then there is the corner of the great female songwriters like Tori Amos, Bjork, and Sia Furler. That pretty much covers it. I can go on for hours but I think these are the few directions which have influenced me most.
She is a cousin of Dutch hardcore DJ DaY-már. When asked in a Loudwire interview who she gets inspired by vocally she mentions Australian singer Sia Furler. Wessels admires Sia's voice and also her song-writing. She's a fan of the horror film genre. Wessels has an art history degree and also has a master's degree in gender studies.