Lie Ren is a male teenager with black, somewhat spiky, long hair and a ponytail that ends midway down his back. There is a magenta streak on the left side of his hair. His eyes match the streak in his hair, and his clothing appears to be influenced by Eastern culture. He wears a dark green diagonally buttoned long-sleeved Tailcoat that is red on the inside, with black and gold trimming and pink cuffs. The trimming goes down the right side of his torso and forms a black collar. This color scheme seems to be influenced to some degree by the lotus flower, which is the meaning of the name Ren. He wears black undersleeves beneath the suit, and light tan pants with black shoes.
Although not much is known about Ren, it can be deduced that he is mellow most of the time and wishes for peace and quiet in a manner, like Blake Belladonna. All in all, he seems very much in control of himself, as shown by his calm and deliberate response to the appearance of the black portion of a King Taijitu. He also may not be a morning person, as seen from his groan from having to get out of bed to get ready for the Initiation. He seems to be indifferent to Nora Valkyrie's jumpy personality and has shown to be very patient, even when dealing with his hyperactive childhood friend. Nora has called him "the perfect student", possibly implying he may be something of an intellectual. However, this is not to say that he is completely humorless. He appeared to be slightly playful after finding Nora in the Emerald Forest. Ren also is indicated to be a bit of a cook as he makes pancakes for the team in Episode 14.
Lie Ren is a very capable fighter, and can hold his own against creatures like the King Taijitu. He demonstrates peak physical ability, being able to do various acrobatics. He can move and react with impressive speed. Ren appears to be proficient in martial arts, using palm thrusts and various stances when fighting the King Taijitu. Along with his physical abilities, Ren can also skillfully wield his weapons and effectively uses them for both ranged and melee combat. However, he has been shown to run out of breath rather quickly after chasing after Nora, and was shown collapsing after the fight with the Death Stalker. This may be because he expended most of his energy fighting the King Taijitu before finding Nora.
Ren appears to have a high degree of control over his Aura. When fighting in the Emerald Forest, he first uses it defensively by forming a shield against the attacks of a King Taijitu. After tearing it's fangs off, Lie Ren uses his Aura offensively by blasting the black King Taijitu's fang through its own eye, blowing its head to pieces.
Despite this however, he still has a very limited amount of stamina, collapsing from when they defeated the Death Stalker. His averaged endurance was also seen after defeating the King Taijitu, in which he was seen catching his breath. This could have been caused by the heavy amount of his aura he used which is needed to fight as shown in Jaunedice.
- He is the first character revealed whose emblem color is not recognizable at first glance, as it does not appear to be a prominent color in his apparel.
- "Ren" is Japanese for "lotus", hence his emblem. "Lie" (烈) is Chinese for "ardent." "Lie Ren" (猎人) is Chinese for "huntsman."
- His name is similar to Hua Mulan. Hua means "prosper" but also means "flower" and Mulan means "magnolia." The similar symbolism is one of many reasons fans suppose Mulan was used as the basis for Ren's character. In addition, Monty has stated that "All of team JNPR disguised themself in the other gender in their inspired character", something that Hua Mulan is famous for.
- To some degree, he physically resembles Monty Oum, his voice actor.
- Ren has a habit of brushing himself off whenever he does something that could have caused him to get dirty.
- This could mean he wants to be clean and respectable at all times.
- He seems to wear the same clothes when he sleeps.
- Ren is the first character to win a fight without assistance from his primary weapon.
- In the episode Players and Pieces, Ren appeared exhausted, twice. The first time was after he and Nora rode on an Ursa, and the second time was after team JNPR killed the Death Stalker. Since Ren was voiced by the series' creator, Monty Oum, this could be a nod to Monty's tweets about his sleep deprivation (since he worked hard on the series).
- He has a habit of resting his coffee mug on his palm instead of holding it by its handle.
- Ren has somewhat of a resemblance to Soul Eater character Death the Kid as both wield automatic pistols, both do not need their weapon to defeat certain opponents, and have a colored-streak on the side of their hair.