Argyle was a good-hearted earth pony who studied the history of Twilight Sparkle and her friends and, just like his daughter, believed that earth ponies, unicorns and pegasi could be friends again one day.
Unlike the other earth ponies, Argyle paid no mind to the supposed "history" that demonized the other pony tribes and made sure to share his own beliefs and wisdom with his daughter, Sunny Starscout, raising her to hope and believe that ponykind could be united in friendship and harmony as they once were. Despite being disparaged and disbelieved by others, like Phyllis Cloverleaf, Arygle never got angry or frustrated by his fellow earth ponies' bigotry and misguided beliefs, rather pitying them and feeling sad that they wouldn't open their hearts and minds to something better than fear and distrust.
Argyle was a warm and loving father, fondly remembered by his daughter long after his passing, and she strove to see Argyle's dream fulfilled despite the naysayers and odds she faced, ultimately succeeding in bringing ponykind back together, honoring her father's memory and legacy.
He had a light blue coat, a royal blue mane and tail with white and purple streaks, cornflower-blue hooves, and purple eyes. His eyebrows and sideburns were dark violet. He used to wear dark maroon-rimmed glasses and a wooden pendant hollowed out with the outline of Twilight Sparkle's cutie mark. His cutie mark was a yellow shooting star.