During holidays in Versoix, Switzerland, with his maternal grandparents, Nicholas spent hours in his grandfather's garage, watching him maintain his Jeep collection.

[8] In an interview with historian Filip-Lucian Iorga, Nicholas recalled the time spent with King Michael, and how he had been allowed to drive one of his cars, a Ford which once belonged to General George S. Patton; the vehicle was given to his grandfather by Queen Anne's paternal uncle Prince Felix of Bourbon-Parma as a gift.

[9] As a descendant of Queen Victoria of the United Kingdom and King Christian IX of Denmark, he regularly met with many of his extended relatives.

[12] Before enrolling for university he took a five-year "Gap year", where:[11] Nicholas’s first major appearance in Romania was on 19 April 1992 on Easter Day along with his grandparents King Michael I and Queen Anne and with his mother and her second husband Alexander Nixon.

[16] Since the beginning of 2008, de Roumanie Medforth-Mills has become more involved in the public life of Romania, taking part, for instance, at the 2008 UNITER theatre gala[17] and in visits throughout the country with his aunt, Crown Princess Margareta, and Radu Duda.

[18][19][20][21][22][23] In 1997, Romanian monarchists intended to ask Michael to designate a male heir-presumptive from the House of Hohenzollern in keeping with the rules of the last royal constitution which were based on agnatic primogeniture and Salic law.

In 2005, King Michael told Nicholas that he could choose to have the chance of becoming a "prince of Romania" which would mean assuming responsibility in a conscious manner by starting to work for the country.

[3] The former king took the decision after considering that Romania needed a ruler marked by modesty and moral principles, respect and thought for others after the "reign and life" of his eldest daughter, Crown Princess Margareta, will have finished.

In issuing the declaration, the former king expressed the hope that "Nicholas will find in future years a suitable way to serve the ideals and use the qualities that God gave him".

[32][33][34] On 8 November 2017, during Michael I's final illness, Crown Princess Margareta filed a complaint with Swiss police alleging that Nicholas tried to force his way into his grandfather's home.