Sleebs got rescued at a young age by Geralt and Jaskier who killed the mages using him as an experiment on genetics. He was then brought to Kaer Morhen where he formed an extremely strong bond with Jaskier, to the point of having panic attacks if he wasn't always with him, and hating Geralt for being so close to him. The rest of the time, he struggled with emotions, only showing deep possessiveness over Jaskier. But thanks to many residents of Kaer Morhen, he grew up to the complete opposite: a bubbly, emotive and empathic adult.

He underwent the first Trial of the Grasses (that had become harmless), granting him augmented strength and stamina. But it was decided not to go further because of his frail body type. Instead, he became a bard apprentice under Jaskier. He is also a natural magic user, although not trained, he can't do much. In the end, he decided to do what he loved most and did best: indulging in earthly pleasure and taking care of the now numerous inhabitants of Kaer Morhen. He made his own mix of fisstech, rendering it entirely harmless without sacrificing the effects, and started sex work, asking mostly for sweets as payment.

Although he can have some difficult moments, especially when his PTSD is triggered, he's known to be a great friend and lover to all those who know him. He eventually gets pregnant of quadruplets (all from different fathers) whom he raises happily with his two boyfriends: Rey and Azy.