Yankee Ω wa Kemono Ou-sama no Mono!
Delinquent uke gets transported to fantasy world where he is seme's mate. Uke turn out to be omega and seme is an alpha, next in line to the throne and is the beast king.
The Falling Merman
Uke is merman, seme is wolf. Both were captive, seme became agent and went to save uke. Watching over uke while they decide what to do with uke. Both have powers.
Bakemono no Hanayome
Uke is nine tailed fox, seme is wolf. Both clans don't get along, and fox clan doesn't like uke for his tails. Uke and seme are in an arranged marriage as a truce between clans.
Hatsujou Kemono Biyori
1st Couple - Uke is a house cat and seme is a street cat. Uke goes into heat but doesn't know what it is, asks seme to help him at park. 2nd Couple - Uke used to be leader of cats, seme idolized uke. Uke ends up leaving for a bit and returns to town but gets caught. Saved by seme.
Caressing The Nipples of My Hibernating Bear