90s(?) book series about two people transported to a parallel medieval world, she joins city watch, he becomes wizard [duplicate]

Question

I must have read his in the nineties. I think it was a series of books.

The first book starts off with a woman in a cabin in a modern-day American desert. I think a biker dude turns up, and then a wizard appears with a baby, and transports them to a parallel medieval world. The woman joins the city watch, protecting the baby, and the biker dude becomes an apprentice to the wizard.

I remember one scene where the biker dude casts a spell to change his appearance to a dung beetle, to sneak past some guards thinking it would be inconspicuous, but the locals had never seen a dung beetle before.

The book was written in English.

Answer 1

Possibly the Time of the Dark, part one of Barbara Hambly's Darwath Trilogy? The land of Darwath, a fantasy-medieval type kingdom on another world is under attack by the shapeshifting alien Dark Ones, and the wizard Ingold flees to Earth with the baby prince. Ending up at a cabin in the California desert Ingold meets a woman named Gil and the mechanic Rudy. Somehow the three end up back in Darwath, where Rudy discovers a talent for magic. I've only read the first of the trilogy, don't know how the rest turns out.