Ruben “Ruby” Martinez Jr is the secondary protagonist on the Netflix series "On My Block".

He is portrayed by Jason Genao.

 Character Description

Ruby Martinez is a 14-15-year-old high school student. He is of Mexican descent and has brown hair and tanned skin color.

Throughout the Series

Chapter One Ruby along with Monse, Cesar and Jamal spy in on a party, only to be confronted by a member of the Santos. They run away after gunshots are fired and regroup at Ruby's house to speak with Mario. A few months go by and Monse returns from writing camp, Ruby informs Monse that the group is on bad terms with Cesar. Jamal tells Monse and Ruby is annoyed. Monse confronts Cesar and attacks him, Ruby and Jamal intervene and an angry Monse stops hanging out with the three. Monse gets tired of Jasmine and starts hanging out with Ruby and the rest again.


Physical Appearance

Ruby is 5'1 and is the shortest of all his friends. He is a gentleman. He is of Mexican descent with wavy dark brown hair and brown eyes. He has a chubby face and is mistaken as a child often because of his lacking height. He is averagely built.


He's a little obsessed with girls and was especially interested in Olivia, who used to live in his house before passing away.

He is what can be described as a "hopeless romantic". This is proven throughout the season by the grandiose gestures he makes for Olivia. Despite being rejected on multiple occasions, he continued to pursue Olivia, in hopes of one day becoming the "love of her life".

He is also a very determined individual. Whenever there is a problem at hand, Ruby is always the one to assess and eliminate it as soon as possible. It is hinted throughout the season that he was somewhat of deep-seated jealousy towards Cesar if the relationship between Cesar and Olivia was anything to go by. He is very insecure and strives to better himself daily, even if at times he is unaware that everyone around him loves him for who he is.

He is described by Jamal as the "wizard of words" because he is a gifted speaker, although his nervous babble when talking to Oscar in Chapter Two lead to Cesar getting "promoted" in the gang and having to take on more responsibilities.


Appearances (28/28)

Season 1 (10/10)

Season 2 (10/10)

Season 3 (8/8)


  • He does taxes for other people, despite being around the age of fourteen.
  • He doesn't believe in the Yeti. (Chapter One)
  • He says that he sweats profusely when he's nervous. (Chapter Two)
  • He has appeared in every single On My Block episode since Season 1
  • In Season 2, he suffers from PTSD because of the events at Olivia’s Quinceanera


  • "I mean, for starters, I’m small. there’s nothing about me that’s even remotely intimidating and, actually, on numerous occasions, I’ve been told that just looking at me makes people laugh. I also don’t do anybody any favors by being the smartest person in the room. And no one wants to feel dumb when they can’t pick up what I’m laying’ down. It’s belittling, you follow? (Jamal & Monse: mm mm) You see? this is what I’m talking about. I transcend the universal plane of thought and linger on the precipice of the celestial realm. I can’t even keep up with myself. But it’s who I am." (Chapter Two)

  • "I'm wearing indigo tonight. [...] I thought we should claim colors to avoid outfit clashes." (Chapter Three)

  • "You got two options.Either come clean to your folks or come clean to your folks. Karma's a bitch, dude." (Chapter Six)


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To view the Ruby Martinez gallery, click here.

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