TRC - The Runesmith Chronicles — A Universe from the Mind of BluDraygn

A young farmer with an ailing mother gets help from a large, blue-skinned, demon-like woman called an oni in return for a little bit of sexy time. As their relationship grows, they discover the young man has mysterious abilities and a special affinity for magic which will lead him on a journey that puts him into contact, and often deep inside, a variety of monster girls / (Reviews)

Book 2 - Kal sets out after Ikuno's disappearance and his first major challenge has him infiltrating the monstergirl slave trade to save a captured dog girl. But that's just the beginning...

Kal can fly now, which means it is time to go get Ikuno. However, the ability to fly doesn't help much when trying to cross a vast desert filled with unknown hazards. This brings him to Fazal, a city on the edge of the Sulerin Desert and a dangerous place for those unaccustomed to its intrigue. Kal quickly realizes things become a lot more deadly when a skilled assassin has you in their sights.

First Name, Second Name: The blacksmith's son, Devlin Fittlegault, sets out on his first adventure to rescue a captured knight and earns a new name. Last Name Parts 1-2: Devlin is older and leads his own adventuring party. After winning a costly battle, his employer refuses to pay up. His revenge nets him a new title, and something more.