Asking for a friend, they are getting a rescue dog, and wish to change the name. But the people who fostered the animal for 10 months, dubbed them fitful! A name they don’t fancy, but don’t want to confuse the dog too, too much.
Not to “fight the premise,” but I don’t think your friends are giving the dog enough credit. Dogs generally will readily accept a new name, no matter how different it is from the previous. As long as you’re consistent with the new name, he’ll figure it out pretty quickly. If anything, calling him something very similar but slightly different will confuse the dog more than just giving it a completely different name.
On some other thread, I saw the term “pibble” as a cutesy nickname for a pit bull. Of course, you haven’t said what breed the dog is – nor does the dog know, and anyhow, it’s bound to be only ‘mostly’ – but maybe it would work for your friend’s new best friend.
I agree with this. Dogs can adapt to a new name quite well. I got my rescue at about 9 months old with the names listed in his papers as “Red” and “Frankie.” I knew I didn’t like either of those, so I took him for a walk and asked him his name. He didn’t exactly tell me, but he’s been Cinnamon ever since. See my avatar to see if that’s appropriate.
I misread the premise of the OP and was initially thinking of something relating to “Fretful Porpetine.”
II’ve always just used both names for a bit, and then switched to just the new name.
I also note that my dog Reese responds equally well to pet names (pun intended) like “buddy”, “puppy”, “gooboy”, “hey-ey”, “brown dog”, and so on. Anything I’ve called him he picks up on. At most it might take a single repeat to get his attention.