Ronno is not a very kind deer. When he is older, he challenges Bambi to fight because he hates him and wants to mate with Faline, whom he had a crush on since childhood. Though it's very clear she has no interest in him, and Bambi finally takes up the challenge when Ronno starts driving Faline away, using his antlers to force her to go where he wants her. He is very disrespectful to everyone, including his own mother, who he practically bullies as a fawn, and yet still goes running to at the slightest sign of danger. As a fawn he is a braggart, a bully, a liar, a coward, manipulative and generally has no redeeming qualities whatsoever, seeming to mainly be brought about by his pride at having his antlers starting to come in and his spots having gone.
As a fawn, Ronno had dark auburn fur, green eyes, a hole in his right ear and budding antlers.
As a young adult, Ronno remains the same but his eyes change from green to light brown and has antlers with three points on them.
Judging by his appearance, Ronno is roughly a few months older than Bambi since as fawns, Ronno had budding antlers and no spots whilst Bambi had no antlers and still had spots (until the end of Bambi II). As young adults, Ronno has three points on his antlers whilst Bambi only has two.
In the original movie, Ronno first appears at Bambi's daydream with Faline. He appears from a bush where Faline disappeared into, Bambi still in his daydream nearly runs into him when his daydream ends off suddenly when Ronno appears. Though he has no lines in the film, his intentions are clear. He immediately began threatening Faline away from Bambi until Bambi charges at him. The two begin combat, Ronno overtaking Bambi at first. At the end of the fight, Ronno is thrown over a cliff and falls into the water below and leaves. It is unknown if he survived the wildfire, as the only scene he appears in was the fight scene and he is not mentioned at all either.
In Bambi II, Ronno is given much more personality and unlike in the previous film, here he has dialogue. When Bambi and his friends were watching the Groundhog, Ronno scares him back into his hole with a "BOO!" and laughs while the other animals leave in disappointment, but he stops them and tells them that he saw a man, and butted him with his antlers. This is clearly a tall tale he pulls just to garner respect. Faline, who knows that it is impossible for a fawn to defeat a man, politely and without offending, says it was unbelievable, though with noticeable sarcasm in her voice. Bambi, who really believes that Ronno had done such a feat (as a testament to his innocent naivety), thinks it is unbelievable too, though he says it in awe. Ronno, who thinks that Bambi doesn't believe him and is hinting at him being a liar, challenges Bambi to a fight. Thumper tells Bambi to clobber him. Ronno continues to goad Bambi by insulting his name, "Bambi? Isn't that a girl's name?" and laughing, insisting that Bambi spar with him while backing the smaller fawn up against a tree. Just before the two fawns get in a fight, Ronno's mother calls him and he reluctantly returns to her before he could fight with Bambi, though he scolds "MA! How many times do I have to tell ya, don't bother me when I'm trying to make new friends!!" to which his mom replies "Sorry, dear!"
Later in the film, Ronno, who has become infatuated by her beauty (or the fact that she is the only doe beside the mothers that we see), tells Faline about himself, but Faline still believes Ronno isn't what he claims to be and shows clear displeasure in his company. She hears Bambi screaming and rushes to check on him. Ronno, upset about Bambi garnering Faline's attention away from him, shows up to insult Bambi and says that he witnessed Bambi freeze with fear out on a meadow when Man's dogs arrived, right in front of his father The Great Prince. Ronno tells Bambi not to feel bad as if there weren't cowards, you wouldn't tell who the brave ones were. Bambi replies that he's not a coward and "roars" at Ronno. When Ronno tries to get Faline to leave with him, Bambi comes to her defense to which Ronno starts to tease Bambi again this time about being with Thumper and Flower. Thumper pushes Bambi forward, trying to encourage him to stand up to Ronno, only for Bambi to accidentally knock Ronno down into the mud. Angry, Ronno starts to chase Bambi and Thumper and while chasing them, Bambi jumps over a chasm and then Bambi runs into his father while Ronno backs away into the bushes. Bambi's father is impressed by the jump and father and son start making their way back home. Ronno tries to jump over but falls into a mud pit.
He shows up again during the "First Sign of Spring" musical number, running with the other bucks, taunting Bambi with a raised tail and a haughty stance before taking off to join the bucks. When the Great Prince runs past him, he gives an awed "Woah!", his expression to change to anger and jealousy as Bambi runs past him. He speeds up, trying to overtake Bambi and keep up with the Great Prince, only for Bambi to easily overtake him and run alongside his father, both outdistancing Ronno and leaving him well behind with the rest of the bucks.
Later on, he shows up and taunts Bambi while Mena is taking Bambi to his new home, saying that he wanted to say goodbye, thought they were pals, and really felt sorry for Bambi having a father that was so ashamed of him, he'd give him away. This makes Bambi angry enough to attack, and in the fight, they mistakenly push Mena into a snare. She tells them to get out of there immediately in a panic, the bell on the trap immediately alerting hunters to their location and the barking of dogs clear in the distance. Ronno, revealing his cowardice, runs off crying for "Mommy" but Bambi stands where he is, frozen in fear.
Ronno shows up after Faline and Bambi kiss and swears revenge for stealing Faline, vowing to return but he trips on a turtle, which snaps his nose, with him screaming "GET IT OFF!!!" repeatedly and jumping around in a panic, which incites Flower to say "See? I told you turtles were scary."
Ronno made two appearances in the series. In the episode "Goofy's Menu Magic", he can be seen waiting on the line for some of Goofy's soup. In "House of Genius", he was seen waiting to be seated when Donald and Daisy were sleeping on the job. Although Ronno does not appear in Mickey's House of Villains, it is believed that he took part in the takeover.
- In the first film, instead of lines, Ronno is expressed through ominous music (just like Man).
- He named his antlers Stab and Jab in Bambi II.
- In the original book that Bambi was based on, Ronno was said to have been one of the young princes of the forest, alongside Bambi and another deer named Karus.
- In the midquel, when young Ronno forces Faline to leave and his fight with Bambi near the end, refers to when the two are at maturity.
- It is hinted Ronno is jealous that Bambi is the son of the Great Prince.
- Ronno has brown eyes as a buck, but as a fawn, his eyes are green.