Ren is a slim young man of average height with dark, spiky hair reaching down to his shoulders, with long strands framing his face, and a short ponytail at the back of his head. Each of his eyebrows juts upwards in a pair of thin spikes, and he’s distinguished by his dark skin, a result of Tanning Lacrima he used on himself. After the 7-years time skip, the only differences in Ren’s appearance seem to reside in his hair, these being the lack of his former ponytail and the presence of two bangs framing and partially covering his face's sides.
Ren's attire consists of a black suit with the jacket left open, bearing Blue Pegasus' symbol on its left shoulder, over a leopard patterned shirt, whose similarly open collar reveals a small metal necklace circling his neck, and polished, dark dress shoes. Seven years following the destruction of Tenrou Island, Ren's attire has remained virtually the same, with the exceptions of the missing Guild Mark on the left shoulder of his black suit and the new color of the shirt underneath.
Like the rest of the Trimens, Ren behaves like a typical womanizer in that he usually charms any female (regardless of the age) he meets for the first time. If he is around a girl he always tries to act like a tsundere, but in Lucy's case it wasn't very effective. He doesn't get along with other men, (except his team members) probably because he considers them as his rivals in love. During Ren's battle against Araña, while Sherry was cheering for him, it was revealed that he's in a relationship with her, but as Ren's a tsundere, he doesn't admit it.