Robin - initially referred to as just the "Blonde-Haired Boy" - is a major character in the game, and is initially believed to be one of the test subjects revived during Monika's curse. Throughout Aya's adventure, Robin tries to get her to come with him so that they can flee from the mansion together.

Robin is shown to be a rather stoic young man, and is rather mature for his age. It's likely this is due to an incident in his past, which resulted in the death of his parents and his sister, which forced him to look at life a little differently. Robin appears to love his departed family dearly - especially his little sister, whom he regrets being unable to save - as he did not wish to view Alfred or Aya as replacements for them.

In spite of his maturity, Robin is shown to have some naivety. When he first tries to get Aya to follow him, he never considered the possibility that Aya would be afraid of him upon noticing he was missing an eye, though after that happens, he makes sure to cover up his empty eye socket with bandages. An Old Man also implies that he's too trusting towards Monika, who he thinks is simply using the young boy to further her own agenda.

Robin is shown to be very determined and focused on his goals, as he promised a sleeping Aya that he would do his best to protect her and her family. After he gets revived by Monika and asked to escape the mansion with Aya during the anniversary of Monika's death, he does what he can to try and do so, warning Aya of the dangers and trying to convince her that her quest to save her father is pointless. At the game's climax, he asks Aya to never forget the people that suffered under Alfred, as all of them were ignored and forgotten by the world at large.

IF Mode reveals that, while his revival has nothing to do with Monika's curse - since he was revived before that - he chooses to have Aya and Maria believe that it is, as he feels if they knew the truth, they would make him pay. He also doesn't want to drag them down since they're trying to move forward with their lives. This may imply he doesn't think too highly of himself.