As a young child, Ren was much more cheerful and even a little sassy according to his mother. He was also shown to be very naive, not understanding how to use Lien or thinking he could buy sake. He also was easily frightened, shown when the bullies looked at him and he was about to run away.

Ren is usually mellow and wishes for peace and quiet, much like Blake Belladonna. He seems very much in control of himself, as shown by his calm and deliberate response to the appearance of the black half of a King Taijitu. He is unbothered by Nora Valkyrie's bubbly and contrasting personality, showing a great deal of patience when dealing with his hyperactive, happy-go-lucky childhood friend.

Ren is also shown to be quite studious, as seen in "Welcome to Beacon", in which he openly agrees with Neptune Vasilias as to how libraries should be only for reading. Likewise, he is well informed about villages in between kingdoms, such as when he informs Ruby about Higanbana in "Family". However, this is not to say that he is completely humorless. He is slightly playful after finding Nora in the Emerald Forest, during the events of "The Emeral Forest". This is also shown when he and Nora were debating over team names in "The Next Step". Ren is also indicated to be a bit of a cook, as he makes pancakes for the team in "Forever Fall Pt 2". However, not everything he cooks is well received, as the nutrition drink he prepared in "Destiny" made Nora ill even though he drank it with no problems.