These are portraits of two pairs of the younger “McClain Boys” (sons of Nathan and Mary McClain). The photographic prints are mounted on cards—in this case, cards larger than a cartes-de-visite, but smaller than a cabinet card. The portraits do not appear to have been taken at the same time—possibly even several years apart, based on differences in clothing styles.
If the above portrait was indeed taken in 1905, Arthur was 21 and Ellery was 16. If there was a particular event that prompted getting this portrait, I can’t guess what it might have been.
Frank McClain passed away in April 1909, days after his 23rd birthday, apparently of Type 1 Diabetes, as discussed in this previous post. The latest this portrait could have been taken is probably February 1909, since Frank was ill for nearly two months before he passed away. What a shock it must have been when a guy who looked perfectly healthy in this portrait fell sick and died so suddenly, not long after it was taken!
Ray was 21, or very nearly so, when this portrait was taken.