Santillan began learning to skate in 1996.[1] He teamed up with Olivia Oltmanns in September 2009.[3] The pair's international debut took place in September 2010 at a Junior Grand Prix (JGP) event in Graz, Austria. Their best JGP placement, 7th, came in September 2011 in Riga, Latvia.
Oltmanns/Santillan moved up to the senior level in the 2014–15 season. They finished 11th at the 2015 U.S. Championships. Trudi Oltmanns coached the pair in Minnesota.[4]
Pfund underwent surgery in mid-2016 due to two torn ligaments in her right foot and returned to the ice three months later.[7] She and Santillan finished 8th at the 2016 Cup of China. Following the event, she had an amniotic stem cell injection to treat tendinitis in her anterior tendon and a bone cement injection for a chronic bruise in her talus bone.[7] In January 2017, Santillan had a strained rotator cuff in his right shoulder.[7] The pair placed 5th at the 2017 U.S. Championships.
In October 2020, Pfund and Santillan announced their intention to represent Switzerland in competition, but were told by the U.S. Figure Skating Federation that they would have to wait a year to be released.[8] In July 2021, they announced they were allowed to represent Switzerland for the 2021-2022 season.[9]
On March 18, 2022, they announced their retirement from competitive skating.[10]