Araff

I was supposed to study dirt for a living. Instead, I fell in love with the alien engineer who could rebuild a starship blindfolded - and helped him take down a trafficking network hiding inside the Trade Council itself.

Alissa came to Mars to study soil. She left it aboard an alien warship, one of four human women taken by a species desperate to survive.
Araff has no bonding marks. No ancient biology telling him she's his. He has scarred hands, a workshop full of half-repaired engines, and a talent for building things no one else can. When he starts building her a wrench, his people's oldest courting gift, she realizes she's already chosen him back.
But someone is hiding a trafficking network inside the reformed council, and every piece of engineering they follow leads to a name that doesn't exist. Kellan wasn't the architect.
He was only the broker.

Book Two of A Bride for the Alien Series. Standalone HEA. Slow-burn, workplace romance, size difference, relationship-first-bond-second, matched-tools courting, and one very steamy maintenance closet.