Hi, I am glad that you found your way to the Pepin forum.
Since you say that you are sooooo new to genealogy, I must point out a couple of things.
First of all ,if you have traced your ancestors, you should never say “I believe I am a descendant of Guillaume.”You really must have proof of every generation.If you skip or make a mistake in any one of the generations the end result is not the same.There were 3 Pepins that pioneered New France (Québec).Guillaume Pepin, Antoine Pepin-aka-Lachance and Robert Pepin all came from France.
Second Rootsweb is a very poor source to trace your ancestors.Use the information only as a guide and not fact.There are too many mistakes found there that never get corrected.Now that the Drouin collection is available at Ancestry, it would be an excellent source.
My line of Pepins is very short.Guillaume’s daughters Madeleine and Marie-Ursule were my 7th great grandmothers.
You say that your maiden name is “Papin” and I realize that people were poorly educated back then and that their names picked up a lot of different spellings.I went to PRDH’s (University of Montreal) to check out the two names.They have recorded all the various spelling from all contracts before 1799.Pepin was spelled 12 different ways with Pepin used the most and Papin had 6 different spellings.These two names never crossed before 1799 according to what I see at PRDH. “Pa” and “Pe” do NOT sound the same in French and even a poor speller, most likely would not cross those two names.Yet I admit that it may have happened, so be very careful to have proof for every generation starting with your grandfather and his parents.
If your line goes Guillaume, Jacques, Jean (not Jean Baptiste) and Charles-Francois, then according to Jette, Jean married Jacqueline de Billy in 1705.
Arthur (how fun) my grandfather, father and brother were all named Arthur.
I doubt that you will be able to find a direct line from your Pepin or Papin to the Kings of the Franks.If you ever find out that one of your pioneering ancestors is Marie-Catherine de Baillon married to Jacques Miville in 1669, then you will have a very well proven line to: King-of-the-Franks, Pepin III "The Short".He was the Father of: Charlemagne King-of-the-Franks-&-Emperor.Pepin III was my 37th great grandfather.Every generation starting with me to him was proven. It was my Lavoie ancestors that led to Marie-Catherine de Baillon.
It is my understanding that the Pepin surname was used by many of the people that worked the land under these Pepin kings, like Charlemagne’s son “King-of-Italy, Pepin I”.If the Pepins from Quebec could be traced to the Kings someone would have done it by now.4 renowned genealogists worked for years to prove Catherine de Baillon’s line. They were able to do this because the monks kept the records of royalty in caves during the many European battles and wars.Oh well good luck.
I posted the little bit that I have o the Pepins so that individuals are made aware that the Pepins date to New France (Québec) in the mid 1600s.