Excellent info on Roy - that's the ticket! Thanks kypaige22 and please thank your mom, too.
Since we've shown that Theodore in 1900 census is indeed "your" Theodore, it is highly likely the 13 year old "Regn Larson" is Roy - because that's a close match to the records and (significantly) to your family stories and letters.
So where are we with Roy? We have a working hypothesis that he is the boy in the 1900 census with Theodore and Julia. That record says he was born in May. The other records we posted, for the guy we think is him, say he was born in May.
The christening record says he was baptized in September, a long wait - unusual. Are you sure it says September? The two dates 02 September and 09 September suggest a birth and baptism separated by a week, which is more typical. What is the place name on the record? What is the year (are you assuming a year, or is it noted?) Who found it, how did your family acquire it? I would like to see that record. Can you post a jpeg? At least, can you type it word for word, and post? That would be hard, I know. It's quite difficult for other people to react and process quick and incomplete references to records. In searching for Roy's birth in Norway, I have not found it - and at this point, the continued searching of church pages, page by page, reading each name, seems kind of silly since you now say you already have the record.
Understand that these records in Norwegian archives are not transcribed and indexed. Seekers must turn each page of the churchbook, clicking through each digital image one by one, and reading each name, one by one. The process is laborious, and to be avoided - if possible. ;-D
What makes you think Louise Larsen is Roy's maternal grandmother? (mother of Josephine Nathalie Knudsen) This thread has no evidence for Josephine's parents. Can you add facts and sources in this regard?
Since Ole Christian was a seaman (according to Marie's 1888 birth record), perhaps Roy arrived USA ca 1892 with his father, on father's ship? Just wondering why we haven't found immigration for him.Found 1907 travel, but he seemingly had come to USA previously (source: as previously posted).
You are making good progress in shaping your contributions into "genealogy style" messages. Very helpful. As you continue on with your genealogy, as you seek collaborators, do post as many facts as you have, complete as possible (for example, if a person has a middle name, include it when naming the person; and if he/she has a formal name as well as a nickname, say so; and if he/she has a Norwegian name as well as an Americanized name, reveal that from the start ). Then tie each fact to its source or sources. Post transcriptions of your records for the benefit of collaborators (type up what the records say), just as you see volunteer researchers doing for your benefit. After awhile, it starts to seem natural to formulate your posts in this fashion.