The Crimson Witch by Dean Koontz
Jake Turnet is stuck in a world destroyed by nuclear holocaust after an overdose of PBT, a psychic chemical that opened the doorway. This world, unlike his own is populated by warlocks and witches and all manner of mythical creatures. He has to find a way to get back to his worldline but he would have to get past an ambitious ruler and his minions with the help of witches, Kell and Cheryn, and a vegetarian dragon, Kaliglia. This book, published in 1972 (now out of print), is a mix of fantasy, sci-fi, and romance. It wasn't stated how Cheryn, the Crimson Witch of Eye Mountain, met Jake. How their relationship developed wasn't explained either but Cheryn finds herself madly in love with Jake and ended up helping him. The battle scenes using magic weren't bad but repetitive. The best part of this book for me was when Jake, Cheryn, and Kaliglia passed through the gate to get to Jake's worldline. The ending seemed like it was rushed. Cheryn suddenly gained so much...