i would just like you to know that my Louis Le bisque companion is not promoting. if this will be any help full i am level 24 in cool ranch and the Louis Le bisque is level 0
He will promote. He is also my musketeers first in line companion as he is absolutely wonderful (gets a 9 square area bombs drop after his second promotion and his range of attack increases as he levels).
I trust you are going to the tavern cellar? Little ladder leading down in most taverns, which is where he'll give the quest. Without being spoilery, he'll tell you to go to Gullet and talk to a fox for his promotion questline. He becomes a Crab Gunner when it is complete.
I just completed his 1st promotion last night on one of my characters.