There were two Aments in Twain's life. If the name had been Smith or Brown, who would notice, but Ament is not a common name. The first one was the printer Sammy apprenticed under in Hannibal, as noted here:

http://www.authorama.com/boys-life-of-mark-twain-7.html
“I was supposed to get two suits of clothes a year, but I didn’t get them. I got one suit and took the rest out in Ament’s old garments,
The other was "The Rev. Mr. Ament, of the American Board of Foreign Mission" as noted here:
https://en.wikisource.org/wiki/To_the_Person_Sitting_in_Darkness
Could it be that these two were related? If so, what a coincidence. And might Twain have had an immediate negative reaction to the surname, even if subconsciously? Who can hear the surnames Hitler, Stalin, Mussolini, or Dinosaur (as in "Barney the") without an immediate repulsion?
Other interesting similarities in names in Twain's world are Lam[b,p]ton, Langdon, Langhorne; also Paine and Paige. - B. Clay Shannon